Control apparatus

ABSTRACT

A control apparatus is used in a power transmission system for transmitting power with a magnetic resonance manner to a power reception apparatus from a power transmission apparatus. The control apparatus comprises a power control unit configured to control a power transmission state in which transmission power of the power transmission apparatus is controlled in a state in which a power transmission target power reception apparatus is detected, and a test power transmission state in which transmission power of the power transmission apparatus is controlled in a state in which the power transmission target power reception apparatus is not detected.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of U.S. patent applicationSer. No. 15/032,479 filed on Apr. 27, 2016, which is the U.S. NationalPhase of PCT Application No. PCT/JP2014/078240 filed on Oct. 23, 2014,which claims benefit of Japanese Patent Application No. 2013-223741filed on Oct. 28, 2013, Japanese Patent Application No. 2013-223742filed on Oct. 28, 2013, Japanese Patent Application No. 2013-223749filed on Oct. 28, 2013, Japanese Patent Application No. 2013-223750filed on Oct. 28, 2013, Japanese Patent Application No. 2013-223751filed on Oct. 28, 2013, Japanese Patent Application No. 2013-223763filed on Oct. 28, 2013, and Japanese Patent Application No. 2013-223201filed on Oct. 28, 2013, the entirety of all applications herebyincorporated by reference.

TECHNICAL FIELD

The present disclosure relates to a control apparatus used in a powertransmission system for transmitting power with a magnetic resonancemanner to a power reception apparatus from a power transmissionapparatus.

BACKGROUND ART

Conventionally, a technique has been studied of wirelessly transmittingpower from a power transmission apparatus to a power receptionapparatus. For example, as such a radio power transmission system, amagnetic resonance manner has been devised. Specifically, by adjusting adrive frequency of each resonator so that a resonator of the powertransmission apparatus and a resonator of the power reception apparatusresonate with each other at a specific frequency, power is wirelesslytransmitted from the power transmission apparatus to the power receptionapparatus (for example, Patent Literature 1).

It is considered that the power transmission apparatus does not graspthe power reception apparatus existing around the power transmissionapparatus. Alternatively, it is considered that the power transmissionapparatus does not grasp the power reception apparatus operating evenwhen grasping the power reception apparatus existing around the powertransmission apparatus. Alternatively, it is considered that the powertransmission apparatus does not grasp the power reception apparatusnewly installed.

Therefore, it is preferable that the power transmission apparatustransmits a search signal for searching a power transmission targetpower reception apparatus, and detects the power transmission targetpower reception apparatus by information transmitted from the powerreception apparatus.

However, when the power reception apparatus does not have a powerstorage unit such as a capacitor and a secondary battery, the powerreception apparatus is not able to transmit the information if the poweris not transmitted from the power transmission apparatus. In addition,when the power stored in the power storage unit is not able to providepower necessary for communication even if the power reception apparatushas the power storage unit such as the capacitor and the secondarybattery, the power reception apparatus is not able to transmit theinformation if the power is not transmitted from the power transmissionapparatus.

In this way, due to power shortage of the power reception apparatus,there is a case where the power reception apparatus is not able tocommunicate, and the power transmission target power reception apparatusmay not be detected.

CITATION LIST Patent Literature

Patent Literature 1: Japanese application publication No. 2011-166883

SUMMARY

A control apparatus according to the present disclosure is used in apower transmission system for transmitting power with a magneticresonance manner to a power reception apparatus from a powertransmission apparatus. The control apparatus comprises a powercontroller configured to control a first power transmission state inwhich power is transmitted at a first amount of power, and a secondpower transmission state in which power is transmitted at a secondamount of power greater than the first amount of power.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a power transmission system 100according to a first embodiment.

FIG. 2 is a diagram illustrating a power transmission apparatus 10according to the first embodiment.

FIG. 3 is a diagram illustrating a power reception apparatus 20according to the first embodiment.

FIG. 4 is a diagram illustrating state transition of the powertransmission apparatus 10 according to the first embodiment.

FIG. 5 is a diagram for describing types of the power receptionapparatus 20 according to the first embodiment.

FIG. 6 is a sequence diagram illustrating a power transmission methodaccording to the first embodiment.

FIG. 7 is a sequence diagram illustrating a power transmission methodaccording to the first embodiment.

FIG. 8 is a sequence diagram illustrating a power transmission methodaccording to the first embodiment.

FIG. 9 is a diagram for describing a trigger E according to a secondembodiment.

FIG. 10 is a diagram illustrating state transition of the powertransmission apparatus 10 according to a third embodiment.

FIG. 11 is a sequence diagram illustrating a power transmission methodaccording to a modification of a fourth embodiment.

FIG. 12 is a diagram for describing a power transmission methodaccording to the modification of the fourth embodiment.

FIG. 13 is a diagram illustrating state transition of the powertransmission apparatus 10 according to a sixth embodiment.

FIG. 14 is a diagram illustrating state transition of the powerreception apparatus 20 according to a modification of the sixthembodiment.

FIG. 15 is a diagram illustrating a power transmission system 100according to a seventh embodiment.

FIG. 16 is a diagram illustrating a power transmission apparatus 10according to the seventh embodiment.

FIG. 17 is a diagram illustrating a power reception apparatus 20according to the seventh embodiment.

FIG. 18 is a diagram illustrating an application scene of the powertransmission system 100 according to the seventh embodiment.

FIG. 19A is a diagram illustrating a relationship between powertransmission distance and power transmission efficiency according to theseventh embodiment.

FIG. 19B is a diagram illustrating a relationship between the powertransmission distance and transmission power of the power transmissionapparatus 10, and between the power transmission distance and powerreception voltage of the power reception apparatus 20.

FIG. 20 is a flow diagram illustrating a control method according to theseventh embodiment.

FIG. 21 is a flow diagram illustrating a control method according to amodification of the seventh embodiment.

DESCRIPTION OF EMBODIMENTS Summary of First Embodiment

A control apparatus according to a first embodiment is used in a powertransmission system for transmitting power with a magnetic resonancemanner to a power reception apparatus from a power transmissionapparatus. The control apparatus comprises a power control unitconfigured to control a power transmission state in which transmissionpower of the power transmission apparatus is controlled in a state inwhich a power transmission target power reception apparatus is detected,and a test power transmission state in which transmission power of thepower transmission apparatus is controlled in a state in which the powertransmission target power reception apparatus is not detected.

In the first embodiment, since power is transmitted to the powerreception apparatus by introducing the test power transmission state,the power transmission target power reception apparatus can be detectedwithout depending on a power state of the power reception apparatus.

First Embodiment

(Power Transmission System)

In the following, the power transmission system according to the firstembodiment is described. FIG. 1 is a diagram illustrating a powertransmission system 100 according to the first embodiment. FIG. 2 is adiagram illustrating a power transmission apparatus 10 according to thefirst embodiment. FIG. 3 is a diagram illustrating a power receptionapparatus 20 according to the first embodiment.

As illustrated in FIG. 1, the power transmission system 100 includes thepower transmission apparatus 10 and the power reception apparatus 20,and is a system for transmitting power with a magnetic resonance mannerto the power reception apparatus 20 from the power transmissionapparatus 10. In FIG. 1, one power reception apparatus 20 isexemplified; however, a plurality of the power reception apparatuses 20can be provided to the power transmission system 100. The powerreception apparatus 20 has, for example, sensors provided at eachposition in a room (human detection sensor, temperature sensor,illumination sensor), and is operated by power received from the powertransmission apparatus 10. The power transmission apparatus 10 isembedded, for example, in the ceiling or under the floor of the room tosupply the power to each of the sensors.

In the first embodiment, the power transmission system 100, although itis not limited thereto, can have an EMS (Energy Management System)configured to control power of a consumer's facility. The EMS includesan HEMS (Home Energy Management System), a BEMS (Building EnergyManagement System) provided to a building, an FEMS (Factory EnergyManagement System) provided to a factory, and an SEMS (Store EnergyManagement System) provided to a store.

As illustrated in FIG. 2, the power transmission apparatus 10 has apower transmission side resonator 11, a power transmission module 12,and a communication module 13.

The power transmission side resonator 11 is a resonator adjusted toresonate at a specific frequency. Specifically, as illustrated in FIG.2, the power transmission side resonator 11 is configured by a capacitorC and an inductance L (coil). For example, by adjusting capacity of thecapacitor C, a resonance frequency of the power transmission sideresonator 11 can be adjusted to the specific frequency.

The power transmission module 12 is a module for sending out power.Specifically, as illustrated in FIG. 2, the power transmission module 12is connected directly to a commercial power supply, or connected to thecommercial power supply via an AC adapter.

Here, when the power transmission module 12 is connected directly to thecommercial power supply, the power transmission module 12 has aconverter 12A and an inverter 12B. The converter 12A and the inverter12B generate AC power of the specific frequency. In such a case, theconverter 12A converts the AC power supplied from the commercial powersupply to DC power, and the inverter 12B converts the DC power outputfrom the converter 12A to the AC power of the specific frequency.

On the other hand, when the power transmission module 12 is connected tothe commercial power supply via the AC adapter, the power transmissionmodule 12 has only the inverter 12B. The inverter 12B generates the ACpower of the specific frequency. In such a case, the inverter 12Bconverts the DC power output from the converter 12A to the AC power ofthe specific frequency.

In these cases, magnitude of transmission power of the powertransmission apparatus 10 is determined by magnitude of the AC poweroutput from the inverter 12B.

The communication module 13 is a module for communicating with the powerreception apparatus 20. The communication module 13 can communicate withthe EMS described above. Specifically, the communication module 13 has acommunication unit 13A and a control unit 13B.

The communication unit 13A is connected to the power reception apparatus20 wirelessly or via a wire, and transmits a signal to the powerreception apparatus 20, and receives a signal from the power receptionapparatus 20. For example, as described later, the communication unit13A transmits a search signal for searching the power receptionapparatus 20. The communication unit 13A transmits an informationrequest for requesting transmission of information for specifying a typeof the power reception apparatus 20. On the other hand, thecommunication unit 13A receives an authentication ID of the powerreception apparatus 20. The authentication ID is returned from the powerreception apparatus 20 depending on the search signal. The communicationunit 13A receives the information for specifying the type of the powerreception apparatus 20. The information for specifying the type of thepower reception apparatus 20 is returned from the power receptionapparatus 20 depending on the information request.

The control unit 13B controls the power transmission module 12 and thecommunication module 13. For example, the control unit 13B controlstransmission power of the power reception apparatus 20 in each stateillustrated in FIG. 4 described later. In other words, in the firstembodiment, the control unit 13B configures a power control unitconfigured to control a power transmission state (a power transmissionstate and an intermittent power transmission state described later) inwhich the transmission power of the power transmission apparatus 10 iscontrolled in a state in which the power transmission target powerreception apparatus 20 is detected, and a test power transmission statein which the transmission power of the power transmission apparatus 10is controlled in a state in which the power transmission target powerreception apparatus 20 is not detected. In addition, the control unit13B controls the transmission power of the power transmission apparatus10, based on the information acquired by the communication unit 13A.Incidentally, the control unit 13B can be included in the powertransmission module 12 instead of being included in the communicationmodule 13. In addition, the control unit 13B can be provided to anothercontrol apparatus from the communication module 13 and the powertransmission module 12, and the control apparatus can control thecommunication module 13 and the power transmission module 12.

Here, it is preferable that the power transmission target powerreception apparatus 20 is a power reception apparatus 20 authenticatedby the power transmission apparatus 10 (control apparatus). Therefore,it is preferable that the number of power transmission target powerreception apparatuses 20 is the number of power reception apparatuses 20authenticated by the power transmission apparatus 10 (controlapparatus).

Here, it is preferable that the control unit 13B controls powertransmission of the power transmission apparatus 10 to continuouslytransmit when the power transmission target power reception apparatus 20does not have a power storage unit. On the other hand, it is preferablethat the control unit 13B controls power transmission of the powertransmission apparatus 10 to intermittently transmit when the powertransmission target power reception apparatus 20 has the power storageunit. The control unit 13B can combine continuous power transmission andintermittent power transmission when the power reception apparatus 20not having the power storage unit and the power reception apparatus 20having the power storage unit are mixed.

The control unit 13B controls a power transmission interval based on atleast one of the number of power transmission target power receptionapparatuses 20 and the type of the power transmission target powerreception apparatus 20, when controlling power transmission of the powertransmission apparatus 10 to intermittently transmit. For example, thecontrol unit 13B shortens the power transmission interval, as the numberof power transmission target power reception apparatuses 20 increases.Alternatively, the control unit 13B shortens the power transmissioninterval as maximum reception power of the power transmission targetpower reception apparatus 20 is greater.

It is preferable that the type of the power transmission target powerreception apparatus 20 is identified by information indicating themaximum reception power of the power transmission target power receptionapparatus 20, whether or not the power transmission target powerreception apparatus 20 has the power storage unit, or capacity of thepower storage unit included in the power transmission target powerreception apparatus 20. Here, the reception power means power receivedby the power reception apparatus from the power transmission apparatus,and the maximum reception power means maximum power received by thepower reception apparatus from the power transmission apparatus.Incidentally, here, as a parameter for specifying the type of the powerreception apparatus 20, the maximum reception power of the powertransmission target power reception apparatus 20 has been mentioned;however, it is not limited thereto; it can be necessary power forexecuting a predetermined control by the power reception apparatus 20,that is, necessary reception power.

For example, the control unit 13B increases the transmission power ofthe power transmission apparatus 10, as the number of power transmissiontarget power reception apparatuses 20 is greater. Here, the transmissionpower means power to be sent out from the power transmission apparatus.Alternatively, the control unit 13B increases the transmission power ofthe power transmission apparatus 10, as the maximum reception power ofthe power transmission target power reception apparatus 20 is greater.

Here, it is preferable that the control unit 13B controls thetransmission power of the power transmission apparatus 10 tocontinuously transmit when the power transmission target power receptionapparatus 20 does not have the power storage unit. On the other hand, itis preferable that the control unit 13B controls the transmission powerof the power transmission apparatus 10 to intermittently transmit whenthe power transmission target power reception apparatus 20 has the powerstorage unit. The control unit 13B can combine continuous powertransmission and intermittent power transmission when the powerreception apparatus 20 not having the power storage unit and the powerreception apparatus 20 having the power storage unit are mixed.

The control unit 13B controls the power transmission interval based onat least one of the number of power transmission target power receptionapparatuses 20 and the type of the power transmission target powerreception apparatus 20, when controlling the transmission power of thepower transmission apparatus 10 to intermittently transmit. For example,the control unit 13B shortens the power transmission interval, as thenumber of power transmission target power reception apparatuses 20increases. Alternatively, the control unit 13B shortens the powertransmission interval, as the maximum reception power of the powertransmission target power reception apparatus 20 is greater.

As illustrated in FIG. 1, the power reception apparatus 20 has a powerreception side resonator 21, a power reception module 22, and acommunication module 23.

The power reception side resonator 21 is a resonator adjusted toresonate at a specific frequency. Specifically, as illustrated in FIG.3, the power reception side resonator 21 is configured by the capacitorC and the inductance L (coil). For example, by adjusting capacity of thecapacitor C, a resonance frequency of the power reception side resonator21 can be adjusted to the specific frequency.

The power reception module 22 is a module for receiving power.Specifically, as illustrated in FIG. 3, the power reception module 22has a rectifier circuit 22A, a DC/DC converter 22B, a load 22C, and apower storage unit 22D.

The rectifier circuit 22A converts DC power supplied from the powerreception side resonator 21 to AC power. The DC/DC converter 22Bperforms step-up conversion or step-down conversion of the powersupplied from the rectifier circuit 22A. The load 22C is operated by thepower transmitted by the power transmission apparatus 10 and suppliedfrom the DC/DC converter 22B, and is, for example, the sensors describedabove. The power storage unit 22D stores the power transmitted by thepower transmission apparatus 10 and supplied from the rectifier circuit22A. The power storage unit 22D is, for example, an electric doublelayer capacitor, a secondary battery, or the like.

In FIG. 3, a case is exemplified in which the power reception module 22has the power storage unit 22D; however, the embodiment is not limitedthereto. That is, the power reception module 22 may not have the powerstorage unit 22D.

The communication module 23 is a module for communicating with the powertransmission apparatus 10. The communication module 23 can communicatewith the EMS described above. It should be noted that the communicationmodule 23 is operated by the power received from the power transmissionapparatus 10. Specifically, the communication module 23 has acommunication unit 23A and a control unit 23B.

The communication unit 23A is connected to the power transmissionapparatus 10 wirelessly or via a wire, and transmits a signal to thepower transmission apparatus 10, and receives a signal from the powertransmission apparatus 10. For example, as described later, thecommunication unit 23A receives the search signal for searching thepower reception apparatus 20. The communication unit 23A receives aninformation request for requesting transmission of information forspecifying the type of the power reception apparatus 20. On the otherhand, the communication unit 23A transmits an authentication ID of thepower reception apparatus 20 depending on the search signal. Thecommunication unit 23A transmits the information for specifying the typeof the power reception apparatus 20 depending on the informationrequest.

The control unit 23B controls the power reception module 22 and thecommunication module 23. For example, the control unit 23B suppliesappropriate power to the load 22C by control of the DC/DC converter 22B.Alternatively, the control unit 13B controls the load 22C depending onan instruction received from the EMS.

(State Transition of Power Transmission Apparatus)

In the following, state transition of the power transmission apparatusaccording to the first embodiment is described. FIG. 4 is a diagramillustrating state transition of the power transmission apparatus 10according to the first embodiment.

As illustrated in FIG. 4, the state of the power transmission apparatus10 includes a stop state, a standby state, a power transmission state,an intermittent power transmission state, and a test power transmissionstate.

The stop state is a state in which power transmission is completelystopped. In detail, the stop state is a state in which the powertransmission apparatus 10 is not started.

The standby state is a state in which power is not transmitted, however,power transmission is ready. The standby state is a state in which thepower transmission target power reception apparatus 20 is not detected,and a state in which the power supply of the power transmissionapparatus 10 is started.

The power transmission state is a state in which power is continuouslytransmitted to the power transmission target power reception apparatus20. The power transmission state is, for example, a state in which poweris continuously transmitted when only the power transmission targetpower reception apparatus 20 not having the power storage unit isdetected. Here, it should be noted that the power transmission state isa state in which the transmission power of the power transmissionapparatus 10 is controlled in a state in which the power transmissiontarget power reception apparatus 20 is detected.

The intermittent power transmission state is a state in which power isintermittently transmitted to the power transmission target powerreception apparatus 20. The intermittent power transmission state is,for example, a state in which power is intermittently transmitted whenonly the power transmission target power reception apparatus 20 havingthe power storage unit is detected. Incidentally, in FIG. 4, theintermittent power transmission state is defined separately from thepower transmission state, however, the intermittent power transmissionstate can be considered to be a part of the power transmission state.Here, it should be noted that the intermittent power transmission stateis a state in which the transmission power of the power transmissionapparatus 10 is controlled in a state in which the power transmissiontarget power reception apparatus 20 is detected.

The test power transmission state is a state in which power istransmitted in a state in which the power transmission target powerreception apparatus 20 is not detected. In detail, the test powertransmission state is a state in which power is transmitted so that asignal (for example, authentication ID described above) can be returnedfrom the power reception apparatus 20 by supplying necessary power forthe communication module 23 of the power reception apparatus 20 tocommunicate. Here, it should be noted that the test power transmissionstate is a state in which the transmission power of the powertransmission apparatus 10 is controlled in a state in which the powertransmission target power reception apparatus 20 is not detected.

Incidentally, a power transmission method in the test power transmissionstate can be different from a power transmission method in the powertransmission state and a power transmission method in the intermittentpower transmission state. For example, the power transmission method inthe test power transmission state is a method repeating a powertransmission period in which power is transmitted and a non-powertransmission period in which power is not transmitted. It is preferablethat the power transmission period in the test power transmission stateis longer than the power transmission period in the intermittent powertransmission state. Alternatively, the power transmission method in thetest power transmission state can be a method for continuouslytransmitting transmission power smaller than transmission power in thepower transmission state and the intermittent power transmission state.

A trigger A for transitioning to the standby state from the stop stateis, for example, an event in which the power transmission apparatus 10is started (event in which power is supplied to the power transmissionapparatus 10). A trigger B for transitioning to the stop state from thestandby state is, for example, occurrence of an event in which power isdisconnected of the power transmission apparatus 10. A trigger C to keepthe standby state is occurrence of an event in which the powertransmission target power reception apparatus 20 is not detected.

A trigger D for transitioning to the power transmission state from thestandby state is occurrence of an event in which the power transmissiontarget power reception apparatus 20 not having the power storage unit isdetected. A trigger E for transitioning to the standby state from thepower transmission state is occurrence of an event in which all of thepower transmission target power reception apparatuses 20 detected are nolonger detected. Alternatively, the trigger E is occurrence of an eventin which power transmission stop is requested from all of the powertransmission target power reception apparatuses 20.

A trigger F for transitioning to the intermittent power transmissionstate from the standby state is occurrence of an event in which thepower transmission target power reception apparatus 20 having the powerstorage unit is detected. A trigger G for transitioning to the standbystate from the intermittent power transmission state is occurrence of anevent in which all of the power transmission target power receptionapparatuses 20 detected are no longer detected. Alternatively, thetrigger G is occurrence of an event in which power transmission stop isrequested from all of the power transmission target power receptionapparatuses 20.

A trigger H for transitioning to the test power transmission state fromthe standby state is occurrence of an event in which the statetransitions to the standby state from the stop state. That is, thetrigger H, same as the trigger A, is occurrence of an event in which thepower transmission apparatus 10 is started (event in which power issupplied to the power transmission apparatus 10). That is, when thepower transmission apparatus 10 is started from the stop state, ittransitions to the standby state, and immediately after that,transitions to the test power transmission state. Incidentally, it cantransition directly to the test power transmission state without goingthrough the standby state from the stop state. Alternatively, thetrigger H is occurrence of an event in which a state (standby state)continues over a certain period of time in which the power transmissionapparatus 10 does not transmit power. Alternatively, the trigger H isuser operation. A trigger I for transitioning to the standby state fromthe test power transmission state is occurrence of an event in which thetest power transmission state continues over a certain period of time.Alternatively, the trigger I is occurrence of an event in which aresponse signal to a search signal (for example, authentication ID,category information) is received from the power reception apparatus 20.In addition, it can transition directly to the power transmission statewithout going through the standby state from the test state. Inaddition, the trigger for transitioning to the power transmission statefrom the test state can be a case where the authentication ID isreceived from the power reception apparatus 20 and authenticationsucceeds, or a case where category information is received afterauthentication succeeds. Here, by “authentication succeeds”, it isindicated, for example, that the authentication ID received matches anauthentication ID stored in advance.

(Type of Power Reception Apparatus)

In the following, types are described of the power reception apparatusaccording to the first embodiment. FIG. 5 is a diagram for describingthe types of the power reception apparatus 20 according to the firstembodiment.

As illustrated in FIG. 5, the power reception apparatus 20 is classifiedinto a plurality of categories (for example, category 1-5). The maximumreception power and the application example are associated with each ofthe categories.

In this way, by classifying the power reception apparatus 20 into theplurality of categories in advance, the type of the power receptionapparatus 20 can be notified only by notifying the category of the powerreception apparatus 20 to the power transmission apparatus 10 from thepower reception apparatus 20. From this point of view, the informationfor specifying the type of the power reception apparatus 20 may beinformation for identifying the category of the power receptionapparatus 20 (category information).

It is preferable that the type of the power transmission target powerreception apparatus 20, as described above, is identified by informationindicating the maximum reception power of the power transmission targetpower reception apparatus 20, whether or not the power transmissiontarget power reception apparatus 20 has the power storage unit, orcapacity of the power storage unit included in the power transmissiontarget power reception apparatus 20. Therefore, it is preferable thatthe categories are associated with these pieces of information.

Incidentally, when the power transmission apparatus 10 detects theplurality of power reception apparatuses 20, and the maximum receptionpower calculated from each piece of category information is above themaximum transmission power, power transmission is stopped as an error.Alternatively, even when the power obtained by adding a predeterminedvalue to the maximum reception power is above the maximum transmissionpower, power transmission can be stopped as an error. Alternatively,power can be transmitted at the maximum transmission power instead ofstopping power transmission as an error.

(Power Transmission Method)

In the following, a power transmission method according to the firstembodiment is described. FIGS. 6 to 8 are sequence diagrams illustratingthe power transmission method according to the first embodiment.

First, a case is described of transmitting power to a power receptionapparatus A not having the power storage unit, with reference to FIG. 6.The power reception apparatus A is an example of the power receptionapparatus 20.

As illustrated in FIG. 6, in step S10, the power reception apparatus Atransitions to a signal reception standby state to start operation ofthe load 22C. The signal reception standby state is a state in whichreception of a signal transmitted from the power transmission apparatus10 is waited. Here, the power reception apparatus A is required to holdpower necessary for communication, and be ready to communicate with thepower transmission apparatus 10. For example, it is a state in which thepower transmission apparatus 10 is in the test power transmission state,and power necessary for communication is transmitted to the powerreception apparatus A, and the power reception apparatus A stores thepower transmitted, or a state in which the power reception apparatus Acontinuously receives the power transmitted.

In step S11, the power transmission apparatus 10 transmits the searchsignal for searching the power reception apparatus 20. Step S11 isperformed in the test power transmission state.

In step S12, the power reception apparatus A transmits an authenticationID of the power reception apparatus A to the power transmissionapparatus 10. The power transmission apparatus 10 authenticates thepower reception apparatus A as the power transmission target powerreception apparatus 20 when an authentication ID stored in advance andthe authentication ID received from the power reception apparatus Amatch with each other.

In step S13, the power transmission apparatus 10 transmits to the powerreception apparatus A an information request for requesting transmissionof information for specifying a type of the power reception apparatus A.

In step S14, the power reception apparatus A transmits to the powertransmission apparatus 10 the information for specifying the type of thepower reception apparatus A. For example, the information for specifyingthe type of the power reception apparatus A is the category informationfor identifying the category illustrated in FIG. 5.

In step S15, the power transmission apparatus 10 starts powertransmission depending on the information (for example, categoryinformation) received in step S14. Here, the power transmitted by thepower transmission apparatus 10 can be power depending on theinformation (for example, category information) received in step S14.Here, since it is found that the power reception apparatus A does nothave the power storage unit from the information for specifying the typeof the power reception apparatus A, the power transmission apparatus 10controls the power transmission to continuously transmit power. That is,the power transmission apparatus 10 transitions to the powertransmission state from the standby state.

In step S16, the power reception apparatus A cancels the signalreception standby state to stop operation of the load 22C.

In step S17, the power transmission apparatus 10 transmits the searchsignal for searching the power reception apparatus 20. Transmission ofthe search signal by the power transmission apparatus 10 in step S17,for example, is performed in the power transmission period in whichpower is transmitted.

In step S18, the power transmission apparatus 10 detects that a certainperiod of time has elapsed from transmission of the search signalwithout reply to the search signal. In this case, the power transmissionapparatus 10 determines that the power reception apparatus A has stoppedreceiving power and there is no other power reception apparatus, andstops transmission of the transmission power. That is, powertransmission apparatus 10 transitions to the standby state from thepower transmission state.

Second, a case is described of transmitting power to a power receptionapparatus B having the power storage unit, with reference to FIG. 7. Thepower reception apparatus B is an example of the power receptionapparatus 20.

As illustrated in FIG. 7, in step S20, the power reception apparatus Btransitions to the signal reception standby state to start operation ofthe load 22C. Here, the power reception apparatus B is required to holdpower necessary for communication, and be ready to communicate with thepower transmission apparatus 10. For example, the power transmissionapparatus 10 is in the test power transmission state, and the powernecessary for communication is transmitted to the power receptionapparatus B. Alternatively, the power necessary for communication can beprovided by the power stored in the power storage unit to the powerreception apparatus B.

In step S21, the power transmission apparatus 10 transmits the searchsignal for searching the power reception apparatus 20. In step S21, thepower transmission apparatus 10, for example, can be in test powertransmission state.

In step S22, the power reception apparatus B transmits an authenticationID of the power reception apparatus B to the power transmissionapparatus 10. The power transmission apparatus 10 authenticates thepower reception apparatus B as the power transmission target powerreception apparatus 20 when an authentication ID stored in advance andthe authentication ID received from the power reception apparatus Bmatch with each other. This is regarded that authentication hassucceeded.

In step S23, the power transmission apparatus 10 transmits to the powerreception apparatus B an information request for requesting transmissionof information for specifying a type of the power reception apparatus B.

In step S24, the power reception apparatus B transmits to the powertransmission apparatus 10 the information for specifying the type of thepower reception apparatus B. For example, the information for specifyingthe type of the power reception apparatus B is the category informationfor identifying the category illustrated in FIG. 5.

In step S25, the power transmission apparatus 10 starts powertransmission of the power transmission apparatus 10 depending on theinformation (for example, category information) received in step S24.Here, the power transmitted by the power transmission apparatus 10 canbe power depending on the information for specifying the type of thepower reception apparatus B received in step S24. Here, since it isfound that the power reception apparatus B has the power storage unitfrom the information for specifying the type of the power receptionapparatus B, the power transmission apparatus 10 starts powertransmission of the power transmission apparatus 10 to intermittentlytransmit. That is, the power transmission apparatus 10 transitions tothe intermittent power transmission state from the standby state.

In step S26, the power reception apparatus B cancels the signalreception standby state to stop operation of the load 22C.

In step S27, the power transmission apparatus 10 transmits the searchsignal for searching the power reception apparatus 20. Transmission ofthe search signal by the power transmission apparatus 10 in step S27,for example, is performed in the power transmission period in whichpower is transmitted.

In step S28, the power transmission apparatus 10 detects that a certainperiod of time has elapsed from transmission of the search signalwithout reply to the search signal. The power transmission apparatus 10stops power transmission. That is, the power transmission apparatus 10transitions to the standby state from the intermittent powertransmission state.

Third, a case is described of transmitting power to the power receptionapparatus A not having the power storage unit and the power receptionapparatus B having the power storage unit, with reference to FIG. 8. Thepower reception apparatus A and the power reception apparatus B areexamples of the power reception apparatus 20. The operation illustratedin FIG. 8 is basically a combination of the operation illustrated inFIGS. 6 and 7.

As illustrated in FIG. 8, in step S30, the power reception apparatus Atransitions to the signal reception standby state to start operation ofthe load 22C. Here, the power reception apparatus A is required to holdpower necessary for communication, and be ready to communicate with thepower transmission apparatus 10. For example, the power transmissionapparatus 10 is in the test power transmission state, and powernecessary for communication is transmitted to the power receptionapparatus A.

In step S31, the power transmission apparatus 10 transmits the searchsignal for searching the power reception apparatus 20. Transmission ofthe search signal by the power transmission apparatus 10 in step S31 isperformed in the test power transmission state.

In step S32, the power reception apparatus A transmits theauthentication ID of the power reception apparatus A to the powertransmission apparatus 10. The power transmission apparatus 10authenticates the power reception apparatus A as the power transmissiontarget power reception apparatus 20 when an authentication ID stored inadvance and the authentication ID received from the power receptionapparatus A match with each other. On the other hand, the powerreception apparatus B does not transmit the authentication ID since itdoes not transition to the signal reception standby state.

In step S33, the power transmission apparatus 10 transmits to the powerreception apparatus A an information request for requesting transmissionof information for specifying the type of the power reception apparatusA.

In step S34, the power reception apparatus A transmits to the powertransmission apparatus 10 the information for specifying the type of thepower reception apparatus A. For example, the information for specifyingthe type of the power reception apparatus A is the category informationfor identifying the category illustrated in FIG. 5.

In step S35, the power transmission apparatus 10 starts powertransmission of the power transmission apparatus 10 depending on theinformation (for example, category information) received in step S34.Here, the power transmitted by the power transmission apparatus 10 canbe power depending on the information for specifying the type of thepower reception apparatus A received in step S34. Here, the powertransmission apparatus 10 continuously transmits power to the powerreception apparatus A.

In step S36, the power reception apparatus B transitions to the signalreception standby state to start operation of the load 22C. Here, thepower reception apparatus B is required to hold power necessary forcommunication, and be ready to communicate with the power transmissionapparatus 10. For example, the power transmission apparatus 10 is in thetest power transmission state, and the power necessary for communicationis transmitted to the power reception apparatus B. Alternatively, thepower necessary for communication can be provided by the power stored inthe power storage unit to the power reception apparatus B.

In step S37, the power transmission apparatus 10 transmits the searchsignal for searching the power reception apparatus 20.

In step S38, the power reception apparatus A transmits theauthentication ID of the power reception apparatus A to the powertransmission apparatus 10. The power reception apparatus B transmits theauthentication ID of the power reception apparatus B to the powertransmission apparatus 10.

In step S39, the power transmission apparatus 10 transmits to the powerreception apparatus A the information request for requestingtransmission of the information for specifying the type of the powerreception apparatus A. The power transmission apparatus 10 transmits tothe power reception apparatus B the information request for requestingtransmission of the information for specifying the type of the powerreception apparatus B.

In step S40, the power reception apparatus A transmits to the powertransmission apparatus 10 the information for specifying the type of thepower reception apparatus A. The power reception apparatus B transmitsto the power transmission apparatus 10 the information for specifyingthe type of the power reception apparatus B. For example, theinformation for specifying the types of the power reception apparatus Aand the power reception apparatus B is the category information foridentifying the category illustrated in FIG. 5.

Here, since the power reception apparatus A has already beenauthenticated, transmission of the information request to the powerreception apparatus A in step S39 and transmission of categoryinformation from the power reception apparatus A in step S40 can beomitted.

In step S41, the power transmission apparatus 10 controls powertransmission of the power transmission apparatus 10 depending on theinformation (for example, category information) received in step S40.That is, the power transmission apparatus 10 changes a powertransmission pattern. Here, the power transmission apparatus 10 changesthe power transmission pattern from continuous power transmission at aconstant transmission power to alternate repetition of a state in whichpower is transmitted at transmission power corresponding to the powerreception apparatus A and a state in which power is transmitted attransmission power obtained by adding the transmission powercorresponding to the power reception apparatus A to transmission powercorresponding to the power reception apparatus B. Incidentally, at thistime, the power reception apparatus B can be in a resonance state at thetiming when the power transmission apparatus 10 transmits power at thetransmission power obtained by adding the transmission powercorresponding to the power reception apparatus A to the transmissionpower corresponding to the power reception apparatus B, and can be in anon-resonance state at the timing when the power transmission apparatustransmits power at the transmission power corresponding to the powerreception apparatus A.

Thus, the power transmission apparatus 10 is able to appropriatelytransmit power depending on the case where the power reception apparatusA and the power reception apparatus B exist.

In step S42, the power reception apparatus B cancels the signalreception standby state to stop operation of the load 22C.

In step S43, the power transmission apparatus 10 transmits the searchsignal for searching the power reception apparatus 20.

In step S44, the power reception apparatus A transmits theauthentication ID of the power reception apparatus A to the powertransmission apparatus 10. The power transmission apparatus 10authenticates the power reception apparatus A as the power transmissiontarget power reception apparatus 20 when an authentication ID stored inadvance and the authentication ID received from the power receptionapparatus A match with each other. On the other hand, the powerreception apparatus B does not transmit the authentication ID since itdoes not transition to the signal reception standby state.

In step S45, the power transmission apparatus 10 transmits to the powerreception apparatus A the information request for requestingtransmission of the information for specifying the type of the powerreception apparatus A.

In step S46, the power reception apparatus A transmits to the powertransmission apparatus 10 the information for specifying the type of thepower reception apparatus A. For example, the information for specifyingthe type of the power reception apparatus A is the category informationfor identifying the category illustrated in FIG. 5.

In step S47, the power transmission apparatus 10 controls powertransmission of the power transmission apparatus 10 depending on theinformation (for example, category information) received in step S46.That is, the power transmission apparatus 10 changes a powertransmission pattern. Here, the power transmission apparatus 10 changesthe power transmission pattern from a state in which power istransmitted intermittently at the transmission power obtained by addingthe transmission power corresponding to the power reception apparatus Ato the transmission power corresponding to the power reception apparatusB while power is transmitted continuously at the transmission powercorresponding to the power reception apparatus A, to a state in whichpower is transmitted continuously at the transmission powercorresponding to the power reception apparatus A.

(Function and Effect)

In the first embodiment, since power is transmitted to the powerreception apparatus 20 by introducing the test power transmission state,the power transmission target power reception apparatus 20 can bedetected without depending on a power state of the power receptionapparatus 20.

In detail, the power transmission apparatus 10, in the test powertransmission state, is able to transmit the search signal for searchingthe power reception apparatus 20, accordingly the power receptionapparatus 20 is able to receive the search signal, and is able totransmit the authentication ID depending on the search signal. Thus, thepower transmission apparatus 10, based on the authentication ID, is ableto authenticate the power reception apparatus 20, and is able to detectthe power transmission target power reception apparatus 20.

Summary of Second Embodiment

It is considered that a power transmission apparatus does not grasp apower reception apparatus existing around the power transmissionapparatus. Alternatively, it is considered that the power transmissionapparatus does not grasp a power reception state of the power receptionapparatus even when grasping the power reception apparatus existingaround the power transmission apparatus.

In such a case, it is considered that power may not be appropriatelytransmitted to the power reception apparatus even if the powertransmission apparatus continues to transmit power to the powerreception apparatus. For example, even if power is transmitted to thepower reception apparatus when the power reception apparatus does notexist around the power transmission apparatus, power transmission of thepower transmission apparatus is wasted. Alternatively, even if power istransmitted to the power reception apparatus when the power receptionapparatus is in a state in which the power cannot be received, powertransmission of the power transmission apparatus is wasted.

On the other hand, a control apparatus according to a second embodimentis used in a power transmission system for transmitting power with amagnetic resonance manner to a power reception apparatus from a powertransmission apparatus. The control apparatus comprises a power controlunit configured to control a power transmission state in which powertransmission of the power transmission apparatus is controlled in astate in which a power transmission target power reception apparatus isdetected, and a standby state in which the transmission of transmissionpower of the power transmission apparatus is waited in a state in whichthe power transmission to the power transmission target power receptionapparatus is ready.

In the second embodiment, the power control unit transitions to thestandby state from the power transmission state depending on thepredetermined trigger. That is, power can be appropriately transmittedto the power reception apparatus by introduction of the standby state.

Second Embodiment

In the following, the second embodiment is described. A difference fromthe first embodiment is mainly described below.

Specifically, in the first embodiment, the control unit 13B configuresthe power control unit configured to control the power transmissionstate (power transmission state and intermittent power transmissionstate described later) in which the transmission power of the powertransmission apparatus 10 is controlled in a state in which the powertransmission target power reception apparatus 20 is detected, and thetest power transmission state in which the transmission power of thepower transmission apparatus 10 is controlled in a state in which thepower transmission target power reception apparatus 20 is not detected.

On the other hand, in the second embodiment, the control unit 13Bconfigures a power control unit configured to control the transmissionpower of the power transmission apparatus 10, based on at least one ofthe number of power transmission target power reception apparatuses 20and a type of the power transmission target power reception apparatus20.

(Transition to Standby State from Power Transmission State)

In the following, detail is described of transition to the standby statefrom the power transmission state. As described above, the transitionstrigger E for transitioning to the standby state from the powertransmission state is occurrence of an event in which all of the powertransmission target power reception apparatuses 20 detected are nolonger detected. As a method for detecting the power transmission targetpower reception apparatus 20, for example, a method described below isconsidered.

First, the trigger E is occurrence of an event in which a responsesignal to a search signal (for example, authentication ID) cannot bereceived within a certain period of time from transmission of the searchsignal. Incidentally, it should be noted that the transmission of thesearch signal is periodically performed.

Second, the power transmission target power reception apparatus 20 is apower reception apparatus 20 authenticated, and an authentication periodof the power reception apparatus 20 expires when a certain period oftime has elapsed after authentication processing of the power receptionapparatus 20 is performed. That is, the trigger E is occurrence of anevent in which all of the authentication periods of the power receptionapparatus 20 expire. Incidentally, it should be noted that theauthentication processing of the power reception apparatus 20 isperiodically performed.

Third, the control unit 13B described above controls the transmissionpower of the power transmission apparatus 10 to transmit power atreference power (Wref) in the power transmission state as illustrated inFIG. 9. The trigger E is occurrence of an event in which thetransmission power of the power transmission apparatus 10 is below astop threshold value (Wer) smaller than the reference power (Wref). Insuch a case, it should be noted that the power transmission apparatus 10periodically measures the transmission power of the power transmissionapparatus 10 in the power transmission state.

Here, the reference power (Wref) is acquired by measuring in advance thetransmission power of the power transmission apparatus 10 in a state inwhich the power transmission target power reception apparatus 20 doesnot exist. It is preferable that the reference power (Wref) isassociated with in advance at least one of the number of powertransmission target power reception apparatuses 20 and the type of thepower transmission target power reception apparatus 20. However, thereference power (Wref) can be a fixed value. The stop threshold value(Wer) is, for example, 10% of the reference power (Wref).

Fourth, the control unit 13B described above controls the transmissionpower of the power transmission apparatus 10 to transmit power at thereference power (Wref) in the power transmission state as illustrated inFIG. 9. The control unit 13B adjusts a resonance frequency of the powertransmission apparatus 10 when the transmission power of the powertransmission apparatus 10 is below an adjustment threshold value (Wth)smaller than the reference power (Wref) in the power transmission state.For example, the control unit 13B adjusts the resonance frequency of thepower transmission side resonator 11 so that the transmission power ofthe power transmission apparatus 10 is above the adjustment thresholdvalue (Wth), by adjusting capacity of the capacitor C. The trigger E isoccurrence of an event in which the transmission power of the powertransmission apparatus 10 is below the stop threshold value (Wer)smaller than the adjustment threshold value (Wth). In such a case, itshould be noted that the power transmission apparatus 10 periodicallymeasures the transmission power of the power transmission apparatus 10in the power transmission state. The adjustment threshold value (Wth)is, for example, 90% of the reference power (Wref).

(Function and Effect)

In the second embodiment, the control unit 13B transitions to thestandby state from the power transmission state depending on thepredetermined trigger (trigger E described above). That is, power can beappropriately transmitted to the power reception apparatus bytransitioning to the standby state by an appropriate trigger.

Summary of Third Embodiment

It is considered that a power transmission apparatus does not grasp apower reception apparatus existing around the power transmissionapparatus. Alternatively, it is considered that the power transmissionapparatus does not grasp the power reception apparatus operating evenwhen grasping the power reception apparatus existing around the powertransmission apparatus. Alternatively, it is considered that the powertransmission apparatus does not grasp the power reception apparatusnewly installed.

Therefore, it is preferable that the power transmission apparatustransmits a search signal for searching a power transmission targetpower reception apparatus, and detects the power transmission targetpower reception apparatus by information transmitted from the powerreception apparatus.

However, when the power reception apparatus does not have a powerstorage unit such as a capacitor and a secondary battery, the powerreception apparatus is not able to transmit the information if the poweris not transmitted from the power transmission apparatus. In addition,when the power stored in the power storage unit is not able to providepower necessary for communication even if the power reception apparatushas the power storage unit such as the capacitor and the secondarybattery, the power reception apparatus is not able to transmit theinformation if the power is not transmitted from the power transmissionapparatus.

In this way, due to power shortage of the power reception apparatus,there is a case where the power reception apparatus is not able tocommunicate, and the power transmission target power reception apparatusmay not be detected.

On the other hand, a control apparatus according to a third embodimentis used in a power transmission system for transmitting power with amagnetic resonance manner to a power reception apparatus from a powertransmission apparatus. The control apparatus comprises a power controlunit configured to control a standby state in which the powertransmission of the power transmission apparatus is waited in a state inwhich power transmission to a power transmission target power receptionapparatus is ready, and a search power transmission state in which thepower transmission apparatus intermittently transmits power in a statein which the power transmission target power reception apparatus is notdetected. The power control unit transitions to the search powertransmission state from the standby state depending on a predeterminedtrigger.

In the third embodiment, the power transmission target power receptionapparatus can be detected without depending on a power state of thepower reception apparatus since the power is transmitted to the powerreception apparatus by introducing the search power transmission state.

Third Embodiment

In the following, the third embodiment is described. A difference fromthe first embodiment is mainly described below.

Specifically, in the first embodiment, the control unit 13B configuresthe power control unit configured to control the power transmissionstate (power transmission state and intermittent power transmissionstate described later) in which the transmission power of the powertransmission apparatus 10 is controlled in a state in which the powertransmission target power reception apparatus 20 is detected, and thetest power transmission state in which the transmission power of thepower transmission apparatus 10 is controlled in a state in which thepower transmission target power reception apparatus 20 is not detected.

On the other hand, in the third embodiment, the control unit 13Bconfigures a power control unit configured to control the transmissionpower of the power transmission apparatus 10, based on at least one ofthe number of power transmission target power reception apparatuses 20and a type of the power transmission target power reception apparatus20.

(State Transition of Power Transmission Apparatus)

In the following, state transition is described of the powertransmission apparatus according to the third embodiment. FIG. 10 is adiagram illustrating the state transition of a power transmissionapparatus 10 according to the third embodiment.

As illustrated in FIG. 10, the state of the power transmission apparatus10 includes a search power transmission state in addition to the statesillustrated in FIG. 4 (stop state, standby state, power transmissionstate, intermittent power transmission state, test power transmissionstate).

The search power transmission state is a state in which power istransmitted in a state in which a power transmission target powerreception apparatus 20 is not detected. In detail, the search powertransmission state is a state in which transmission power is transmittedso that a signal (for example, authentication ID described above) can bereturned from the power reception apparatus 20 by supplying necessarypower for the communication module 23 of the power reception apparatus20 to communicate. Incidentally, the power transmission apparatus 10 cantransmit the search signal for searching the power reception apparatus20 via a communication unit 13A in the search power transmission state.In addition, the power reception apparatus 20 can start transmission ofthe search signal when a predetermined time has elapsed aftertransitioning to the search power transmission state and starting powertransmission.

Incidentally, a power transmission method in the search powertransmission state can be different from a power transmission method inthe power transmission state, a power transmission method in theintermittent power transmission state. For example, the powertransmission method in the search power transmission state is a methodrepeating a power transmission period in which power is transmitted anda non-power transmission period in which power is not transmitted, sameas of the test power transmission state. It is preferable that the powertransmission period in the search power transmission state is longerthan the power transmission period in the intermittent powertransmission state.

In the third embodiment, it is preferable that an intermittent period islonger in which power is transmitted by the power transmission apparatus10 (that is, the length of the interval of the power transmission periodor the interval of the non-power transmission period adjacent to eachother in terms of time) in the search power transmission state, as thetime is longer in which a state continues in which the powertransmission target power reception apparatus 20 is not detected.Alternatively, the power transmission period in the search powertransmission state can be changed depending on the time in which thestate continues in which the power transmission target power receptionapparatus 20 is not detected.

In the third embodiment, the control unit 13B controls the transmissionpower of the power transmission apparatus 10 to transmit power atreference power (Wref) when being in the power transmission state. Insuch a premise, it is preferable that the control unit 13B controls thetransmission power of the power transmission apparatus 10 to transmit atpower smaller than the reference power (for example, power of 40% of thereference power (Wref)) in the search power transmission state.Alternatively, the control unit 13B, in the search power transmissionstate, can control the transmission power of the power transmissionapparatus 10 to transmit power at the reference power (Wref) used in apower transmission state immediately before transitioning to the searchpower transmission state. Here, the reference power (Wref) can bemaximum transmission power of the power transmission apparatus 10. Themaximum transmission power is maximum power that can be transmitted bythe power transmission apparatus 10.

A trigger J for transitioning to the search power transmission statefrom the standby state is occurrence of an event in which the standbystate continues over a certain period of time. A trigger K fortransitioning to the standby state from the search power transmissionstate is occurrence of an event in which the search power transmissionstate continues over a certain period of time. Alternatively, thetrigger K is occurrence of an event in which a response signal to asearch signal (for example, authentication ID, and category information)is received from the power reception apparatus 20. Incidentally, thepower transmission apparatus 10 can start transmission of the searchsignal for searching the power reception apparatus 20 when transitioningto the search power transmission state from the standby state, and canstop transmission of the search signal when transitioning to the standbystate from the search power transmission state.

Incidentally, in the above description, although it is supposed that thesearch power transmission state is a different state from the standbystate and the test power transmission state, not limited thereto, forexample, it can be supposed that the search power transmission state isincluded in the standby state or the test power transmission state asone aspect of each of the states.

(Function and Effect)

In the third embodiment, the power transmission target power receptionapparatus 20 can be detected without depending on a power state of thepower reception apparatus 20 since the power is transmitted to the powerreception apparatus 20 by introducing the search power transmissionstate.

Summary of Fourth Embodiment

As a utilizing scene of a magnetic resonance manner, a utilizing sceneis considered in which power is wirelessly transmitted to a plurality ofpower reception apparatuses from one power transmission apparatus.

However, in the technique described above, it is only considered toachieve energy saving by gradually decreasing transmission power of apower transmission apparatus when a power increase request is notreceived from a power reception apparatus.

Therefore, in the utilizing scene in which power is wirelesslytransmitted to a plurality of power reception apparatuses from one powertransmission apparatus, there is room for various improvements toappropriately control the transmission power of the power transmissionapparatus.

On the other hand, a control apparatus according to a fourth embodimentis used in a power transmission system for transmitting power with amagnetic resonance manner to a power reception apparatus from a powertransmission apparatus. The control apparatus comprises a power controlunit configured to configured to control transmission power of the powertransmission apparatus, based on at least one of the number of powertransmission target power reception apparatuses, and a type of the powertransmission target power reception apparatus. The power transmissiontarget power reception apparatus is a power reception apparatusauthenticated by the control apparatus.

In the fourth embodiment, the power control unit controls thetransmission power of the power transmission apparatus, based on atleast one of the number of power transmission target power receptionapparatuses and the type of the power transmission target powerreception apparatus. Therefore, in the utilizing scene in which power iswirelessly transmitted to a plurality of power reception apparatus fromone power transmission apparatus, the transmission power of the powertransmission apparatus can be appropriately controlled.

Fourth Embodiment

In the following, the fourth embodiment is described. A difference fromthe first embodiment is mainly described below.

Specifically, in the first embodiment, the control unit 13B configuresthe power control unit configured to control the power transmissionstate (power transmission state and intermittent power transmissionstate described later) in which the transmission power of the powertransmission apparatus 10 is controlled in a state in which the powertransmission target power reception apparatus 20 is detected, and thetest power transmission state in which the transmission power of thepower transmission apparatus 10 is controlled in a state in which thepower transmission target power reception apparatus 20 is not detected.

On the other hand, in the fourth embodiment, the control unit 13Bconfigures a power control unit configured to control the transmissionpower of the power transmission apparatus 10, based on at least one ofthe number of power transmission target power reception apparatuses 20and the type of the power transmission target power reception apparatus20.

(Function and Effect)

In the fourth embodiment, the control unit 13B of the power transmissionapparatus 10 controls the transmission power of the power transmissionapparatus 10 based on at least one of the number of power transmissiontarget power reception apparatuses 20 and the type of the powertransmission target power reception apparatus 20. Therefore, in theutilizing scene in which power is wirelessly transmitted to a pluralityof power reception apparatuses 20 from one power transmission apparatus10, the transmission power of the power transmission apparatus 10 can beappropriately controlled.

[Modification]

In the following, a modification of the fourth embodiment is described.A difference from the fourth embodiment is mainly described below.

Although it is not particularly mentioned in the fourth embodiment, inthe modification, the power reception apparatus 20 has a function oftransmitting to the power transmission apparatus 10 a start request forrequesting start of power transmission and a stop request for requestingstop of the power transmission.

(Power Transmission Method)

In the following, a power transmission method according to themodification is described. FIG. 11 is a sequence diagram illustratingthe power transmission method according to the modification. Here, acase is exemplified of transmitting power to a power reception apparatusC and a power reception apparatus D each having a power storage unit. Inaddition, a case is exemplified of transmitting continuous power also tothe power reception apparatus having the power storage unit, instead oftransmitting intermittent power.

As illustrated in FIG. 11, in step S50, the power reception apparatus Ctransitions to a signal reception standby state to start operation of aload 22C. Here, power necessary for communication is provided by powerstored in the power storage unit to the power reception apparatus C.

In step S51, the power transmission apparatus 10 transmits the searchsignal for searching the power reception apparatus 20.

In step S52, the power reception apparatus C transmits an authenticationID of the power reception apparatus C to the power transmissionapparatus 10. The power transmission apparatus 10 authenticates thepower reception apparatus C as the power transmission target powerreception apparatus 20 when an authentication ID stored in advance andthe authentication ID received from the power reception apparatus Cmatch with each other. On the other hand, the power reception apparatusD does not transmit the authentication ID since it does not transitionto the standby state.

In step S53, the power reception apparatus C transmits to the powertransmission apparatus 10 the start request for requesting start ofpower transmission. It is preferable that the start request includesinformation indicating reception power desired by the power receptionapparatus C.

In step S54, the power transmission apparatus 10 starts the powertransmission to the power reception apparatus C depending on the startrequest received from the power reception apparatus C.

In step S55, the power reception apparatus D transitions to the standbystate to start operation of the load 22C. Here, power necessary forcommunication is provided by power stored in the power storage unit tothe power reception apparatus D.

In step S56, the power transmission apparatus 10 transmits the searchsignal for searching the power reception apparatus 20.

In step S57, the power reception apparatus C transmits theauthentication ID of the power reception apparatus C to the powertransmission apparatus 10. The power reception apparatus D transmits theauthentication ID of the power reception apparatus D to the powertransmission apparatus 10.

In step S58, the power reception apparatus C transmits to the powertransmission apparatus 10 a stop request for requesting stop of thepower transmission.

In step S59, the power transmission apparatus 10 stops the powertransmission to the power reception apparatus C depending on the stoprequest received from the power reception apparatus C.

In step S60, the power reception apparatus D transmits to the powertransmission apparatus 10 a start request for requesting start of powertransmission. It is preferable that the start request includesinformation indicating reception power desired by the power receptionapparatus D.

In step S61, the power transmission apparatus 10 starts the powertransmission to the power reception apparatus D depending on the startrequest received from the power reception apparatus D.

In step S62, the power reception apparatus C transmits to the powertransmission apparatus 10 a start request for requesting start of powertransmission. It is preferable that the start request includesinformation indicating reception power desired by the power receptionapparatus C.

In step S63, the power transmission apparatus 10 starts the powertransmission to the power reception apparatus C in addition to the powertransmission to the power reception apparatus D depending on the startrequest received from the power reception apparatus C. That is, thepower transmission apparatus 10 transmits power at power obtained byadding power corresponding to the power reception apparatus C to powercorresponding to the power reception apparatus D.

In step S64, the power reception apparatus D transmits to the powertransmission apparatus 10 a stop request for requesting stop of thepower transmission.

In step S65, the power transmission apparatus 10 stops the powertransmission to the power reception apparatus D depending on the stoprequest received from the power reception apparatus D. However, thepower transmission apparatus 10 continues the power transmission to thepower reception apparatus C.

In step S66, the power reception apparatus C transmits to the powertransmission apparatus 10 a stop request for requesting stop of thepower transmission.

In step S67, the power transmission apparatus 10 stops the powertransmission to the power reception apparatus C depending on the stoprequest received from the power reception apparatus C.

Subsequently, timing is described when the power reception apparatus 20generates the power transmission start request and the powertransmission stop request with reference to FIG. 12.

As illustrated in FIG. 12, the power reception apparatus 20 monitorspower stored in a power storage unit 22D. The power reception apparatus20 transmits to the power transmission apparatus 10 a start request forrequesting start of power transmission when the power stored in thepower storage unit 22D is below a first threshold value. On the otherhand, the power reception apparatus 20 transmits to the powertransmission apparatus 10 a stop request for requesting stop of thepower transmission when the power stored in the power storage unit 22Dis above a second threshold value.

Here, the first threshold value is a threshold value at which chargingof the power storage unit 22D should be started. When the power storageunit 22D is an electric double layer capacitor, the first thresholdvalue is a capacitor charging start voltage. The second threshold valueis a threshold value at which the charging of the power storage unit 22Dshould be completed, and is greater than the first threshold value. Whenthe power storage unit 22D is an electric double layer capacitor, thesecond threshold value is a capacitor charging end voltage.

Here, it is preferable that the power reception apparatus 20 transitionsto a resonance state from a non-resonance state when the power stored inthe power storage unit 22D is below the first threshold value (forexample, capacitor charging start voltage). It is preferable that thepower reception apparatus 20 transitions to the non-resonance state fromthe resonance state when the power stored in the power storage unit 22Dis above the second threshold value (for example, capacitor charging endvoltage). The resonance state is a state in which it is possible toresonate with a magnetic field generated from the power transmissionapparatus 10, and the non-resonance state is a state in which it isimpossible to resonate with the magnetic field generated from the powertransmission apparatus 10.

Summary of Fifth Embodiment

In a magnetic resonance manner, when a resonator of a power transmissionapparatus and a resonator of a power reception apparatus resonate witheach other, even if power feeding to the power reception apparatus isnot necessary, power is transmitted to the power reception apparatusfrom the power transmission apparatus. That is, it is not possible toarbitrarily switch whether or not the power reception apparatus receivestransmitted power.

On the other hand, a control apparatus according to a fifth embodimentis used in a power transmission system for transmitting power with amagnetic resonance manner to a power reception apparatus from a powertransmission apparatus. The control apparatus comprises a resonancecontrol unit configured to control a state of a resonator of the powerreception apparatus between a resonance state in which the resonator ofthe power reception apparatus is capable of resonating with a magneticfield generated from the power transmission apparatus and anon-resonance state in which the resonator of the power receptionapparatus does not resonate with the magnetic field generated from thepower transmission apparatus.

In the fifth embodiment, it is possible to arbitrarily switch whether ornot the power reception apparatus receives the transmitted power, byintroduction of the resonance state and the non-resonance state.

Fifth Embodiment

In the following, the fifth embodiment is described. A difference fromthe first embodiment is mainly described below.

Specifically, in the first embodiment, the control unit 13B configuresthe power control unit configured to control the power transmissionstate (power transmission state and intermittent power transmissionstate described later) in which the transmission power of the powertransmission apparatus 10 is controlled in a state in which the powertransmission target power reception apparatus 20 is detected, and thetest power transmission state in which the transmission power of thepower transmission apparatus 10 is controlled in a state in which thepower transmission target power reception apparatus 20 is not detected.

On the other hand, in the fifth embodiment, the control unit 13Bcontrols the transmission power of the power transmission apparatus 10based on at least one of the number of power transmission target powerreception apparatuses 20 and a type of the power transmission targetpower reception apparatus 20.

In addition, in the fifth embodiment, a control unit 23B configures aresonance control unit configured to control a state of a powerreception side resonator 21 between a resonance state in which aresonance frequency of the resonator of the power reception apparatus 20matches a resonance frequency of the resonator of the power transmissionapparatus 10, and a non-resonance state in which the resonance frequencyof the resonator of the power reception apparatus 20 does not match theresonance frequency of the resonator of the power transmission apparatus10. In other words, the resonance state is a state in which it ispossible to resonate with a magnetic field generated from the powertransmission apparatus 10, and the non-resonance state is a state inwhich it is impossible to resonate with the magnetic field generatedfrom power transmission apparatus 10. When the resonator of the powerreception apparatus 20 is in the resonance state, the power receptionapparatus 20 is able to receive power supplied from the powertransmission apparatus 10 due to the fact that the resonator of thepower reception apparatus 20 resonates with the magnetic field generatedfrom the resonator of the power transmission apparatus 10. On the otherhand, when the resonator of the power reception apparatus 20 is in thenon-resonance state, the power reception apparatus 20 is not able toreceive the power supplied from the power transmission apparatus 10since the resonator of the power reception apparatus 20 does notresonate with the magnetic field generated from the resonator of thepower transmission apparatus 10. For example, the control unit 23Badjusts the resonance frequency of the power reception side resonator 21by adjusting capacity of a capacitor C to control the state of the powerreception side resonator 21 between the resonance state and thenon-resonance state.

First, the control unit 23B can make the state of the power receptionside resonator 21 transition to the non-resonance state from theresonance state depending on user operation. Similarly, the control unit23B can make the state of the power reception side resonator 21transition to the resonance state from the non-resonance state dependingon the user operation.

Second, the control unit 23B can control the resonance state of thepower reception side resonator 21 depending on an instruction receivedfrom an EMS. In such a case, the EMS manages the power reception stateof a plurality of power reception apparatuses 20, and instructs statetransition of the resonator of a first power reception apparatusdepending on a power reception state of a second power receptionapparatus. For example, the EMS instructs the first power receptionapparatus to transition to the non-resonance state from the resonancestate when reception power of the second power reception apparatus isbelow a predetermined threshold value. Incidentally, not limited to theEMS, it can be the other control apparatus.

Third, when the control unit 23B is provided to the first powerreception apparatus, the control unit 23B can control the state of theresonator of the first power reception apparatus depending on the powerreception state of the second power reception apparatus. For example,the control unit 23B makes the state of the power reception sideresonator 21 transition to the non-resonance state from the resonancestate, in the first power reception apparatus, when the reception powerof the second power reception apparatus is below the predeterminedthreshold value. Incidentally, the control unit 23B can be configuredseparately from the first power reception apparatus.

Fourth, the control unit 23B can control the state of the resonator ofthe power reception apparatus 20 depending on an amount of power storedin the power storage unit 22D. For example, the control unit 23B makesthe state of the power reception side resonator 21 transition to theresonance state from the non-resonance state when the amount of powerstored in the power storage unit 22D is below the predeterminedthreshold value.

(Power Transmission Method)

In the following, a power transmission method according to the fifthembodiment is described. It should be noted that, in the fifthembodiment, the operation is the same as described above with referenceto FIGS. 6 to 8, except for the followings.

It should be noted that, specifically, in step S10 of FIG. 6, a powerreception apparatus A transitions to the resonance state from thenon-resonance state when the current state is the non-resonance state.

It should be noted that, in step S20 of FIG. 7, a power receptionapparatus B transitions to the resonance state from the non-resonancestate when the current state is the non-resonance state.

In step S26 of FIG. 7, the power reception apparatus B can transition tothe non-resonance state from the resonance state.

It should be noted that, in step S30 of FIG. 8, the power receptionapparatus A transitions to the resonance state from the non-resonancestate when the current state is the non-resonance state.

It should be noted that, in step S36 of FIG. 8, the power receptionapparatus B transitions to the resonance state from the non-resonancestate when the current state is the non-resonance state.

In step S42 in FIG. 8, the power reception apparatus B cancels a signalreception standby state to stop operation of a load 22C. The powerreception apparatus B can transition to the non-resonance state from theresonance state.

(Function and Effect)

In the fifth embodiment, it is possible to arbitrarily switch whether ornot the power reception apparatus 20 receives the transmitted power, byintroduction of the resonance state and the non-resonance state.

Summary of Sixth Embodiment

It is considered that reception power of a power reception apparatus isinsufficient in a case where the number of power reception apparatusesincreases or a case where power consumption of the power receptionapparatus varies, even when transmission power of a power transmissionapparatus is kept constant. On the other hand, when the transmissionpower of the power transmission apparatus is always set to maximumpower, the transmission power of the power transmission apparatusbecomes excessive, and the transmission power of the power transmissionapparatus is wasted. Further, although it is considered that thetransmission power of the power transmission apparatus is controlledindividually depending on a request of the power reception apparatus,control of the transmission power of the power transmission apparatusbecomes complicated.

On the other hand, a control apparatus according to a sixth embodimentis used in a power transmission system for transmitting power with amagnetic resonance manner to a power reception apparatus from a powertransmission apparatus. The control apparatus comprises a power controlunit configured to control a first power transmission state in whichpower is transmitted at a first amount of power, and a second powertransmission state in which power is transmitted at a second amount ofpower greater than the first amount of power.

In the sixth embodiment, the power control unit is able to appropriatelyand simply control the transmission power of the power transmissionapparatus since the power control unit controls an amount oftransmission power in a stepwise manner in the first power transmissionstate and the second power transmission state.

Sixth Embodiment

In the following, the sixth embodiment is described. A difference fromthe first embodiment is mainly described below.

Specifically, in the first embodiment, the control unit 13B configuresthe power control unit configured to control the power transmissionstate (power transmission state and intermittent power transmissionstate described later) in which the transmission power of the powertransmission apparatus 10 is controlled in a state in which the powertransmission target power reception apparatus 20 is detected, and thetest power transmission state in which the transmission power of thepower transmission apparatus 10 is controlled in a state in which thepower transmission target power reception apparatus 20 is not detected.

On the other hand, in the sixth embodiment the control unit 13Bconfigures a power control unit configured to control transmission powerof the power transmission apparatus 10, based on at least one of thenumber of power transmission target power reception apparatuses 20 and atype of the power transmission target power reception apparatus 20.

Here, it is preferable that the power transmission target powerreception apparatus 20 is a power reception apparatus 20 authenticatedby the power transmission apparatus 10 (control apparatus). Therefore,it is preferable that the number of power transmission target powerreception apparatuses 20 is the number of the power reception apparatus20 authenticated by the power transmission apparatus 10 (controlapparatus).

(State Transition of Power Transmission Apparatus)

In the following, state transition is described of the powertransmission apparatus according to the sixth embodiment. FIG. 13 is adiagram illustrating state transition of the power transmissionapparatus 10 according to the sixth embodiment.

As illustrated in FIG. 13, the state of the power transmission apparatus10 includes a stop state, a standby state, a first power transmissionstate, a first intermittent power transmission state, a test powertransmission state, a second power transmission state, and a secondintermittent power transmission state.

The stop state is a state in which power transmission is completelystopped. In detail, the stop state is a state in which the powertransmission apparatus 10 is not started.

The standby state is a state in which power is not transmitted, however,power transmission is ready. The standby state is a state in which thepower transmission target power reception apparatus 20 is not detected,and a state in which the power supply of the power transmissionapparatus 10 is started.

The first power transmission state is a state in which power iscontinuously transmitted to the power transmission target powerreception apparatus 20 at first power. The first power transmissionstate is, for example, a state in which transmission power iscontinuously transmitted when only the power transmission target powerreception apparatus 20 not having a power storage unit is detected. Thefirst power transmission state is a first power transmission state inwhich power is transmitted at the first amount of power as an amount oftransmission power per unit time.

The first intermittent power transmission state is a state in whichpower is intermittently transmitted at a first frequency to the powertransmission target power reception apparatus 20. The first intermittentpower transmission state is, for example, a state in which power isintermittently transmitted at the first frequency when only the powertransmission target power reception apparatus 20 having the powerstorage unit is detected. Incidentally, in FIG. 13, although the firstintermittent power transmission state is separately defined from thefirst power transmission state, the first intermittent powertransmission state can be considered to be a part of the first powertransmission state in which power is transmitted at the first amount ofpower as the amount of transmission power per unit time.

The test power transmission state is a state in which transmission poweris transmitted in a state in which the power transmission target powerreception apparatus 20 is not detected. In detail, the test powertransmission state is a state in which transmission power is transmittedso that a signal (for example, authentication ID described above) can bereturned from the power reception apparatus 20 by transmitting powernecessary for a communication module 23 of the power reception apparatus20 to communicate.

Incidentally, a power transmission method in the test power transmissionstate can be different from a power transmission method in the powertransmission state and a power transmission method in the intermittentpower transmission state. For example, the power transmission method inthe test power transmission state is a method repeating a powertransmission period in which power is transmitted and a non-powertransmission period in which power is not transmitted. It is preferablethat the power transmission period in the test power transmission stateis longer than the power transmission period in the intermittent powertransmission state. Alternatively, the power transmission method in thetest power transmission state can be a method for continuouslytransmitting transmission power smaller than transmission power in thepower transmission state and the intermittent power transmission state.

The second power transmission state is a state in which power iscontinuously transmitted to the power transmission target powerreception apparatus 20 at second power greater than the first power. Thesecond power transmission state is, for example, a state in which poweris continuously transmitted when only the power transmission targetpower reception apparatus 20 not having the power storage unit isdetected. The second power transmission state is a second powertransmission state in which power is transmitted at the second amount ofpower greater than the first amount of power as the amount oftransmission power per unit time.

The second intermittent power transmission state is a state in whichpower is intermittently transmitted to the power transmission targetpower reception apparatus 20 at a second frequency higher than the firstfrequency. The second intermittent power transmission state is, forexample, a state in which power is intermittently transmitted at thesecond frequency when only the power transmission target power receptionapparatus 20 having the power storage unit is detected. Incidentally, inFIG. 13, although the second intermittent power transmission state isseparately defined from the second power transmission state, the secondintermittent power transmission state can be considered to be an aspectof the second power transmission state in which power is transmitted atthe second amount of power greater than the first amount of power as theamount of transmission power per unit time.

A trigger A for transitioning to the standby state from the stop stateis, for example, an event in which the power transmission apparatus 10is started (event in which power is supplied to the power transmissionapparatus 10). A trigger B for transitioning to the stop state from thestandby state is, for example, occurrence of an event in which power isdisconnected of the power transmission apparatus 10. A trigger C to keepthe standby state is occurrence of an event in which the powertransmission target power reception apparatus 20 is not detected.

A trigger D for transitioning to the first power transmission state fromthe standby state is occurrence of an event in which the powertransmission target power reception apparatus 20 not having the powerstorage unit is detected. In the sixth embodiment, a condition of thetrigger D is satisfied, for example, when the number of powertransmission target power reception apparatuses 20 is equal to or lessthan a predetermined number. Alternatively, a condition of the trigger Dis satisfied, for example, when the power reception apparatus 20 having(using) an application (load) in which an amount of variation in powerconsumption is greater than a predetermined value, is not included asthe power transmission target power reception apparatus 20. A trigger Efor transitioning to the standby state from the first power transmissionstate is occurrence of an event in which all of the power transmissiontarget power reception apparatuses 20 detected are no longer detected.Alternatively, the trigger E is occurrence of an event in which powertransmission stop is requested from all of the power transmission targetpower reception apparatuses 20.

A trigger F for transitioning to the first intermittent powertransmission state from the standby state is occurrence of an event inwhich the power transmission target power reception apparatus 20 havingpower storage unit is detected. In the sixth embodiment, a condition ofthe trigger F is satisfied, for example, when the number of powertransmission target power reception apparatuses 20 is equal to or lessthan a predetermined number. Alternatively, a condition of the trigger Fis satisfied, for example, when the power reception apparatus 20 having(using) the application (load) in which an amount of variation in powerconsumption is greater than a predetermined value, is not included asthe power transmission target power reception apparatus 20. A trigger Gfor transitioning to the standby state from the first intermittent powertransmission state is occurrence of an event in which all of the powertransmission target power reception apparatuses 20 detected are nolonger detected. Alternatively, the trigger G is occurrence of an eventin which power transmission stop is requested from all of the powertransmission target power reception apparatuses 20.

A trigger H for transitioning to the test power transmission state fromthe standby state is occurrence of an event in which the statetransitions to the standby state from the stop state. That is, thetrigger H, same as the trigger A, is occurrence of an event in which thepower transmission apparatus 10 is started (event in which power issupplied to the power transmission apparatus 10). That is, when thepower transmission apparatus 10 is started from the stop state, ittransitions to the standby state, and immediately after that,transitions to the test power transmission state. Incidentally, it cantransition directly to the test power transmission state without goingthrough the standby state from the stop state. Alternatively, thetrigger H is occurrence of an event in which a state (standby state)continues over a certain period of time in which the power transmissionapparatus 10 does not transmit power. Alternatively, the trigger H isuser operation. A trigger I for transitioning to the standby state fromthe test power transmission state is occurrence of an event in which thetest power transmission state continues over a certain period of time.Alternatively, the trigger I is occurrence of an event in which aresponse signal to a search signal (for example, authentication ID,category information) is received from the power reception apparatus 20.In addition, it can transition directly to the power transmission statewithout going through the standby state from the test state. Inaddition, the trigger for transitioning to the power transmission statefrom the test state can be a case where the authentication ID isreceived from the power reception apparatus 20 and authenticationsucceeds, or a case where category information is received afterauthentication succeeds. Here, by “authentication succeeds”, it isindicated, for example, that the authentication ID received matches anauthentication ID stored in advance.

A trigger J for transitioning to the second power transmission statefrom the standby state is occurrence of an event in which the powertransmission target power reception apparatus 20 not having powerstorage unit is detected. In the sixth embodiment, a condition oftrigger J is satisfied, for example, when the number of powertransmission target power reception apparatuses 20 is greater than apredetermined number. Alternatively, a condition of the trigger J issatisfied, for example, when the power reception apparatus 20 having anapplication in which an amount of variation in power consumption isgreater than a predetermined value, is included as the powertransmission target power reception apparatus 20. A trigger K fortransitioning to the standby state from the second power transmissionstate is occurrence of an event in which all of the power transmissiontarget power reception apparatuses 20 detected are no longer detected.Alternatively, the trigger K is occurrence of an event in which powertransmission stop is requested from all of the power transmission targetpower reception apparatuses 20.

A trigger L for transitioning to the second intermittent powertransmission state from the standby state is occurrence of an event inwhich the power transmission target power reception apparatus 20 havingthe power storage unit is detected. In the sixth embodiment, a conditionof the trigger L is satisfied, for example, when the number of powertransmission target power reception apparatuses 20 is greater than apredetermined number. Alternatively, a condition of the trigger L issatisfied, for example, when the power reception apparatus 20 having anapplication in which an amount of variation in power consumption isgreater than a predetermined value, is included as the powertransmission target power reception apparatus 20. A trigger M fortransitioning to the standby state from the second intermittent powertransmission state is occurrence of an event in which all of the powertransmission target power reception apparatuses 20 detected are nolonger detected. Alternatively, the trigger M is occurrence of an eventin which power transmission stop is requested from all of the powertransmission target power reception apparatuses 20.

In FIG. 13, the state transition is exemplified between the standbystate and the second power transmission state, however, the embodimentis not limited thereto. For example, the power transmission state of thepower transmission apparatus 10 can transition between the first powertransmission state and the second power transmission state. A triggerfor transitioning to the second power transmission state from the firstpower transmission state is occurrence of an event in which the numberof power transmission target power reception apparatuses 20 is greaterthan a predetermined number, or an event in which the power receptionapparatus 20 having an application in which an amount of variation inpower consumption is greater than a predetermined value, is included asthe power transmission target power reception apparatus 20. On the otherhand, a trigger for transitioning to the first power transmission statefrom the second power transmission state is occurrence of an event inwhich the number of power transmission target power receptionapparatuses 20 is equal to or less than the predetermined number, or anevent in which the power reception apparatus 20 having the applicationin which the amount of variation in power consumption is greater thanthe predetermined value, is not included as the power transmissiontarget power reception apparatus 20.

Similarly, in FIG. 13, state transition is exemplified between thestandby state and the second intermittent power transmission state;however, the embodiment is not limited thereto. For example, theintermittent power transmission state of the power transmissionapparatus 10 can transition between the first intermittent powertransmission state and the second intermittent power transmission state.A trigger for transitioning to the second intermittent powertransmission state from the first intermittent power transmission stateis occurrence of an event in which the number of power transmissiontarget power reception apparatuses 20 is greater than a predeterminednumber, or an event in which the power reception apparatus 20 having anapplication in which an amount of variation in power consumption isgreater than a predetermined value, is included as the powertransmission target power reception apparatus 20. On the other hand, atrigger for transitioning to the first intermittent power transmissionstate from the second intermittent power transmission state isoccurrence of an event in which the number of power transmission targetpower reception apparatuses 20 is equal to or less than thepredetermined number, or an event in which the power reception apparatus20 having the application in which the amount of variation in powerconsumption is greater than the predetermined value, is not included asthe power transmission target power reception apparatus 20.

A trigger N (or, trigger P) for transitioning to the second powertransmission state (or, second intermittent power transmission state)from the first power transmission state (or, first intermittent powertransmission state) is occurrence of an event in which a request isreceived for executing an application of high power consumption, fromthe power reception apparatus 20, and occurrence of an event in which arequest is received indicating that the power reception apparatus 20transitions to a high load state. A trigger O (or, trigger Q) fortransitioning to the first power transmission state (or, firstintermittent power transmission state) from the second powertransmission state (or, second intermittent power transmission state) isoccurrence of an event in which a notification is received indicatingthat execution of the high power consumption application is ended, fromthe power reception apparatus 20, and occurrence of an event in which anotification is received indicating that the state transitions to apower reception state (low load state) from the high load state, fromthe power reception apparatus 20.

Incidentally, in the above-described example illustrated in FIG. 8, thepower transmission state applied to the power reception apparatus A canbe the first power transmission state, and can be the second powertransmission state. Similarly, the intermittent power transmission stateapplied to the power reception apparatus B can be the first intermittentpower transmission state, and can be the second intermittent powertransmission state.

(Function and Effect)

In the sixth embodiment, the control unit 13B is able to appropriatelyand simply control the transmission power of the power transmissionapparatus since the control unit 13B controls the amount of transmissionpower per unit time in a stepwise manner in the first power transmissionstate and the second power transmission state.

[Modification]

In the following, a modification of the sixth embodiment is described. Adifference from the sixth embodiment is mainly described below.Specifically, in the modification, state transition of the powerreception apparatus is mainly described.

(State Transition of Power Reception Apparatus)

In the following, state transition is described of the power receptionapparatus according to the modification. FIG. 14 is a diagramillustrating state transition of the power reception apparatus 20according to the modification.

As illustrated in FIG. 14, the state of the power reception apparatus 20includes a stop state, a standby state, a first power reception state, asecond power reception state.

The stop state is a state in which power reception is completelystopped. In detail, the stop state is a state in which a resonancefrequency of a resonator of the power reception apparatus 20 does notmatch a resonance frequency of a resonator of the power transmissionapparatus 10, and hereinafter, this state is also referred to as anon-resonance state. The non-resonance state is a state in which it isimpossible to resonate with a magnetic field generated from the powertransmission apparatus 10. When the resonator of the power receptionapparatus 20 is in the non-resonance state, the power receptionapparatus 20 is not able to receive power supplied from the powertransmission apparatus 10 since the resonator of the power receptionapparatus 20 does not resonate with the magnetic field generated fromthe resonator of the power transmission apparatus 10.

The standby state is a state in which power is not received, however,the power reception is ready. The standby state is a state in which theresonance frequency of the resonator of the power reception apparatus 20matches the resonance frequency of the resonator of the powertransmission apparatus 10, and hereinafter, this state is also referredto as a resonance state. The resonance state is a state in which it ispossible to resonate with the magnetic field generated from the powertransmission apparatus 10. When the resonator of the power receptionapparatus 20 is in the resonance state, the power reception apparatus 20is able to receive power supplied from the power transmission apparatus10 due to the fact that the resonator of the power reception apparatus20 resonates with the magnetic field generated from the resonator of thepower transmission apparatus 10.

The first power reception state is a state in which power is received atpower smaller than a predetermined threshold value. For example, thefirst power reception state is a state in which an application (load22C) is driven of power consumption smaller than the predeterminedthreshold value. For example, when the power reception apparatus 20 isin the first power reception state, the power transmission apparatus 10operates in the first power transmission state (or, first intermittentpower transmission state) described above. The first power receptionstate is an example of the low load state described above.

The second power reception state is a state in which power is receivedat greater power than the predetermined threshold value. For example,the second power reception state is a state in which an application(load 22C) is driven of greater power consumption than the predeterminedthreshold value. For example, when the power reception apparatus 20 isin the second power reception state, the power transmission apparatus 10operates in the second power transmission state (or, second intermittentpower transmission state) described above. The second power receptionstate is an example of the high load state described above.

A trigger X1 for transitioning to the standby state from the stop stateis, for example, occurrence of an event in which the power receptionapparatus 20 is started. In addition, the trigger X1 can be a trigger toend power reception operation of the power reception apparatus 20. Insuch a case, the power reception apparatus 20 (control unit 23B) adjustsa resonance frequency of a power reception side resonator 21 byadjusting capacity of a capacitor C depending on the trigger X1 totransition to the resonance state. A trigger X2 for transitioning to thestop state from the standby state is, for example, occurrence of anevent in which power is disconnected of the power reception apparatus20. In addition, the trigger X2 can be a trigger to start powerreception operation of the power reception apparatus 20. In such a case,the power reception apparatus 20 (control unit 23B) adjusts theresonance frequency of the power reception side resonator 21 byadjusting the capacity of the capacitor C depending on the trigger X2 totransition to the non-resonance state.

A trigger Y1 for transitioning to the first power reception state fromthe standby state is, for example, occurrence of an event in which anapplication (load 22C) is started of power consumption smaller than thepredetermined threshold value. A trigger Y2 for transitioning to thestandby state from the first power reception state is, for example,occurrence of an event in which the application (load 22C) is ended ofpower consumption smaller than the predetermined threshold value. It ispreferable that the power reception apparatus 20 transmits to the powertransmission apparatus 10 a notification that the trigger Y1 or thetrigger Y2 is detected, depending on detection of the trigger Y1 or thetrigger Y2.

A trigger Z1 for transitioning to the second power reception state fromthe first power reception state is, for example, occurrence of an eventin which an application (load 22C) is started of greater powerconsumption than the predetermined threshold value. A trigger Z2 fortransitioning to the first power reception state from the second powerreception state is, for example, occurrence of an event in which theapplication (load 22C) is ended of greater power consumption than thepredetermined threshold value. It is preferable that the power receptionapparatus 20 transmits to the power transmission apparatus 10 anotification that the trigger Z1 or the trigger Z2 is detected,depending on detection of the trigger Z1 or the trigger Z2.

In addition, when the event occurs of the above trigger Z1 and triggerZ2 from the standby state, it is possible to transition directly to thesecond power reception state without going through the first powerreception state.

Here, it is preferable that permission is necessary of the powertransmission apparatus 10, the EMS, or the like when transitioning tothe second power reception state from the first power reception state.The permission may not be necessary of the power transmission apparatus10, the EMS, or the like when transitioning to the first power receptionstate from the second power reception state.

Summary of Seventh Embodiment

In the guidelines on the utilization of the radio power transmissionsystem, it is defined that power transmission is permitted from a powertransmission apparatus only when a distance between the powertransmission apparatus and a power reception apparatus is within apredetermined distance. In view of such a circumstance, a technique isdemanded for grasping the distance between the power transmissionapparatus and the power reception apparatus, and stopping powertransmission of the power transmission apparatus when needed.

However, to grasp the distance between the power transmission apparatusand the power reception apparatus, it is necessary to provide, forexample, a GPS or an ultrasonic sensor, and it may cause increase insize or cost of the apparatus.

On the other hand, a control apparatus according to a seventh embodimentis used in a power transmission system for transmitting power with amagnetic resonance manner to a power reception apparatus from a powertransmission apparatus. The control apparatus comprises a control unitconfigured to acquire a power transmission voltage of the powertransmission apparatus, or a power reception voltage of the powerreception apparatus. The control unit stops the power transmission ofthe power transmission apparatus when the power transmission voltageacquired is above a power transmission voltage threshold valuecorresponding to maximum power transmission efficiency of the powertransmission apparatus, or when the power reception voltage acquired isbelow a power reception voltage threshold value corresponding to anallowable maximum distance between the power transmission apparatus andthe power reception apparatus.

In the seventh embodiment, the control apparatus stops powertransmission of the power transmission apparatus when the powertransmission voltage is above the power transmission voltage thresholdvalue, or when the power reception voltage is below the power receptionvoltage threshold value. Thus, power transmission can be stopped of thepower transmission apparatus when needed without causing increase insize or cost of the apparatus.

Seventh Embodiment

(Power Transmission System) In the following, the power transmissionsystem according to the seventh embodiment is described. FIG. 15 is adiagram illustrating a power transmission system 100 according to theseventh embodiment. FIG. 16 is a diagram illustrating a powertransmission apparatus 10 according to the seventh embodiment. FIG. 17is a diagram illustrating a power reception apparatus 20 according tothe seventh embodiment.

As illustrated in FIG. 15, the power transmission system 100 includesthe power transmission apparatus 10 and the power reception apparatus20, and is a system for transmitting power with a magnetic resonancemanner to the power reception apparatus 20 from the power transmissionapparatus 10. In FIG. 15, one power reception apparatus 20 isexemplified; however, a plurality of the power reception apparatuses 20can be provided to the power transmission system 100. The powerreception apparatus 20 includes a load operated by power transmitted bythe power transmission apparatus 10. The power reception apparatus 20can be, for example, sensors (human detection sensor, temperaturesensor, illumination sensor) provided at each position in a room, or canbe a portable equipment such as a remote controller, a smart phone, or atablet terminal. The power transmission apparatus 10 is embedded, forexample, in the ceiling or under the floor of the room to transmit powerto the power reception apparatus 20. The power transmission apparatus 10may also be referred to as a PTU (Power Transmitting Unit), and thepower reception apparatus 20 may also be referred to as a PRU (PowerReceiving Unit).

In the seventh embodiment, the power transmission system 100 furtherincludes an EMS (Energy Management System) 30 being an example of thecontrol apparatus configured to control power of a consumer's facility.The EMS 30 includes an HEMS (Home Energy Management System) provided toa home, a BEMS (Building Energy Management System) provided to abuilding, an FEMS (Factory Energy Management System) provided to afactory, and an SEMS (Store Energy Management System) provided to astore.

As illustrated in FIG. 15, the power transmission apparatus 10 has apower transmission side resonator 11, a power transmission module 12,and a communication module 13.

The power transmission side resonator 11 is a resonator adjusted toresonate at a specific frequency. Specifically, as illustrated in FIG.16, the power transmission side resonator 11 is configured by acapacitor C and an inductance L (coil). For example, by adjustingcapacity of the capacitor C, a resonance frequency of the powertransmission side resonator 11 can be adjusted to the specificfrequency.

The power transmission side resonator 11 further has a voltmeter 11A fordetecting voltage of an inductance L. A voltage value detected by thevoltmeter 11A is hereinafter referred to as power transmission voltageof the power transmission apparatus 10.

The power transmission module 12 is a module for transmitting power.Specifically, as illustrated in FIG. 16, the power transmission module12 has an oscillation circuit 12C and a power supply 12D. Theoscillation circuit 12C is a circuit for adjusting a frequency of ACpower supplied from the power supply 12D by using an inverter or anoscillator to a desired frequency to produce the resonance frequency.

The communication module 13 is a module for communicating with the powerreception apparatus 20. The communication module 13 communicates withthe EMS 30 described above. Specifically, the communication module 13has a communication unit 13A and a control unit 13B.

The communication unit 13A is connected to the power reception apparatus20 wirelessly or via a wire, and transmits a signal to the powerreception apparatus 20 and the EMS 30, and receives a signal from thepower reception apparatus 20 and the EMS 30. For example, thecommunication unit 13A transmits a search signal for searching the powerreception apparatus 20. The communication unit 13A transmits aninformation request for requesting transmission of information forspecifying a type of the power reception apparatus 20. On the otherhand, the communication unit 13A receives an authentication ID of thepower reception apparatus 20. The authentication ID is returned from thepower reception apparatus 20 depending on the search signal. Thecommunication unit 13A receives the information for specifying the typeof the power reception apparatus 20. The information for specifying thetype of the power reception apparatus 20 is returned from the powerreception apparatus 20 depending on the information request.

The communication unit 13A transmits to the EMS 30 the powertransmission voltage of the power transmission apparatus 10. Inaddition, the communication unit 13A receives from the power receptionapparatus 20 information indicating received signal intensity of thesignal received by the power reception apparatus 20 from the powerreception apparatus 20. The communication unit 13A transmits to the EMS30 the information indicating the received signal intensity of thesignal received by the power reception apparatus 20.

The control unit 13B controls the power transmission module 12 and thecommunication module 13. For example, the control unit 13B controlstransmission power of the power transmission apparatus 10. Specifically,the control unit 13B controls the transmission power of the powertransmission apparatus 10 by controlling the power supply 12D, based onthe information acquired by the communication unit 13A.

Here, it is preferable that the power transmission target powerreception apparatus 20 is a power reception apparatus 20 authenticatedby the power transmission apparatus 10. Therefore, it is preferable thatthe number of power transmission target power reception apparatuses 20is the number of power reception apparatuses 20 authenticated by thepower transmission apparatus 10.

It is preferable that the type of the power transmission target powerreception apparatus 20 is identified by information indicating receptionpower of the power transmission target power reception apparatus 20,whether or not the power transmission target power reception apparatus20 has a power storage unit, or capacity of the power storage unitincluded in the power transmission target power reception apparatus 20.

For example, the control unit 13B increases the transmission power ofthe power transmission apparatus 10, as the number of power transmissiontarget power reception apparatuses 20 increases. Alternatively, thecontrol unit 13B increases the transmission power of the powertransmission apparatus 10, as the reception power of the powertransmission target power reception apparatus 20 is greater.

As illustrated in FIG. 15, the power reception apparatus 20 has a powerreception side resonator 21, a power reception module 22, and acommunication module 23.

The power reception side resonator 21 is a resonator adjusted toresonate at a specific frequency. Specifically, as illustrated in FIG.17, the power reception side resonator 21 is configured by the capacitorC and the inductance L (coil). For example, by adjusting capacity of thecapacitor C, a resonance frequency of the power reception side resonator21 can be adjusted to the specific frequency.

The power reception side resonator 21 further has a voltmeter 21A fordetecting voltage of the inductance L. A voltage value detected by thevoltmeter 21A is hereinafter referred to as power reception voltage ofthe power reception apparatus 20.

The power reception module 22 is a module for receiving power.Specifically, as illustrated in FIG. 17, the power reception module 22has a rectifier circuit 22A, a DC/DC converter 22B, a load 22C, and apower storage unit 22D.

The rectifier circuit 22A converts AC power transmitted from the powerreception side resonator 21 to DC power. The DC/DC converter 22Bperforms step-up conversion or step-down conversion of the powertransmitted from the rectifier circuit 22A. The load 22C is operated bythe power transmitted by the power transmission apparatus 10, and is,for example, sensors or a communication equipment.

The power storage unit 22D has a storage battery 22E and a voltmeter22F. The storage battery 22E stores the power transmitted by the powertransmission apparatus 10. The storage battery 22E is, for example, anelectric double layer capacitor or secondary battery. The voltmeter 22Fdetects voltage of the storage battery 22E.

In FIG. 17, a case is exemplified in which the power reception module 22has the power storage unit 22D; however, the embodiment is not limitedthereto. That is, the power reception module 22 may not have the powerstorage unit 22D.

The communication module 23 is a module for communicating with the powertransmission apparatus 10 and the EMS 30. It should be noted that thecommunication module 23 is operated by the power transmitted by thepower transmission apparatus 10. Specifically, the communication module23 has a communication unit 23A and a control unit 23B.

The communication unit 23A is connected to the power transmissionapparatus 10 wirelessly or via a wire, and transmits a signal to thepower transmission apparatus 10 and the EMS 30, and receives a signalfrom the power transmission apparatus 10 and the EMS 30. For example, asdescribed later, the communication unit 23A receives the search signalfor searching the power reception apparatus 20. The communication unit23A receives an information request for requesting transmission ofinformation for specifying the type of the power reception apparatus 20.On the other hand, the communication unit 23A transmits anauthentication ID of the power reception apparatus 20 depending on thesearch signal. The communication unit 23A transmits the information forspecifying the type of the power reception apparatus 20 depending on theinformation request.

The communication unit 23A transmits to the EMS 30 the power receptionvoltage of the power reception apparatus 20. In addition, thecommunication unit 23A transmits to the power transmission apparatus 10the information indicating the received signal intensity of the signalreceived from the power transmission apparatus 10. The communicationunit 23A transmits to the EMS 30 the information indicating the receivedsignal intensity of the signal received from the power transmissionapparatus 10.

The control unit 23B controls the power reception module 22 and thecommunication module 23. For example, the control unit 23B suppliesappropriate power to the load 22C by control of the DC/DC converter 22B.Alternatively, the control unit 23B controls the load 22C depending onan instruction received from the EMS 30.

As illustrated in FIG. 15, the EMS 30 has a communication unit 31, amemory unit 32, and a control unit 33.

The communication unit 31 is connected to the power transmissionapparatus 10 wirelessly or via a wire, and transmits a signal to thepower transmission apparatus 10, and receives a signal from the powertransmission apparatus 10. In addition, the communication unit 31 isconnected to the power reception apparatus 20 wirelessly or via a wire,and transmits a signal to the power reception apparatus 20, and receivesa signal from the power reception apparatus 20.

The memory unit 32 stores the information acquired via the communicationunit 31.

In the seventh embodiment, the control unit 33 acquires the powerreception voltage of the power reception apparatus 20. In addition, thecontrol unit 33 acquires the received signal intensity of the signalreceived from the power transmission apparatus 10 by the power receptionapparatus 20. Specifically, the communication unit 31 receives thesignal indicating the power reception voltage of the power receptionapparatus 20 and the received signal intensity of the signal, and thecontrol unit 33 acquires the power reception voltage of the powerreception apparatus 20 and the received signal intensity from thecommunication unit 31.

In the seventh embodiment, the control unit 33 stops power transmissionof the power transmission apparatus when the power reception voltageacquired is below the power reception voltage threshold valuecorresponding to the allowable maximum distance between the powertransmission apparatus and the power reception apparatus.

(Application Scene)

In the following, an application scene is described of the powertransmission system 100 according to the seventh embodiment. FIG. 18 isa diagram illustrating the application scene of the power transmissionsystem 100 according to the seventh embodiment.

As illustrated in FIG. 18, in the seventh embodiment, the powertransmission system 100 includes a power transmission apparatus 10, anEMS 30, a remote controller 210, a smart phone 220, and a tabletterminal 230. The remote controller 210, the smart phone 220, and thetablet terminal 230 are examples of the power reception apparatus 20,and are operated by power transmitted with a magnetic resonance mannerfrom power transmission apparatus 10.

Here, it should be noted that each of the remote controller 210, thesmart phone 220, and the tablet terminal 230 is a portable equipment,and each distance from the power transmission apparatus 10 is not fixed.

In the guidelines on the utilization of the radio power transmissionsystem, from the point of view of safety measures, it is defined thattransmission of power is permitted from the power transmission apparatus10 only when a distance (power transmission distance) is within thedistance of design specification between the power transmissionapparatus 10 and the power reception apparatus 20.

Therefore, it is desirable that power transmission is stopped of thepower transmission apparatus 10 according to the guideline, when thepower transmission distance is, for example, above an allowable maximumdistance defined for each setting of a function of the powertransmission apparatus 10, due to the fact that the power receptionapparatus 20 (remote controller 210, smart phone 220, and tabletterminal 230) is moved. However, for measurement of the powertransmission distance, for example, a GPS or an ultrasonic sensor isnecessary, so that, in the seventh embodiment, as described below, thepower transmission distance is estimated based on the power receptionvoltage of the power reception apparatus 20.

FIG. 19A is a diagram illustrating a relationship between the powertransmission distance and the power transmission efficiency according tothe seventh embodiment. In the magnetic resonance manner, the powertransmission efficiency varies depending on the distance (powertransmission distance) between the power transmission apparatus 10 andthe power reception apparatus 20. Here, the power transmissionefficiency is a ratio of the reception power of the power receptionapparatus 20 to the transmission power of the power transmissionapparatus 10. The power transmission distance is a distance between thepower transmission side resonator 11 and the power reception sideresonator 21.

When the distance between the power transmission apparatus 10 and thepower reception apparatus 20 is a predetermined distance, a degree ofmagnetic coupling becomes optimal between the power transmission sideresonator 11 and the power reception side resonator 21, and the maximumpower transmission efficiency is obtained. The maximum powertransmission efficiency is determined depending on the setting of thefunction of the power transmission apparatus 10. Hereinafter, a minimumvalue is D1, and a maximum value is D2 of the power transmissiondistance when the maximum power transmission efficiency is obtained.

When the power transmission distance is shorter than D1, the degree ofmagnetic coupling becomes excessive between the power transmission sideresonator 11 and the power reception side resonator 21, and the powertransmission efficiency is slightly below a threshold value. Inaddition, when the power transmission distance is longer than D2, thepower transmission efficiency is decreased due to the fact that thedegree of magnetic coupling is reduced between the power transmissionside resonator 11 and the power reception side resonator 21. When thepower transmission distance is above the allowable maximum distancedefined in product specification, the reception power of the powerreception apparatus 20 becomes close to zero. Here, the allowablemaximum distance defined in the product specification is Dmax. Dmax isdefined depending on the setting of the function of the powertransmission apparatus 10.

FIG. 19B is a diagram illustrating a relationship between the powertransmission distance and the transmission power of the powertransmission apparatus 10, and between the power transmission distanceand the power reception voltage of the power reception apparatus 20. Asillustrated in FIG. 19B, the transmission power of the powertransmission apparatus 10 increases as the power transmission distancebecomes longer. In contrast, the reception power of the power receptionapparatus 20 decreases as the power transmission distance becomeslonger. Here, when the power transmission distances are D1, D2, thepower transmission voltages are Vt1, Vt2, respectively. When the powertransmission distance is Dmax, the power reception voltage is Vr1.

That is, when the power reception apparatus 20 is moved away from thepower transmission apparatus 10, a detection value of the voltmeter 11Acontinues to increase. When the detection value of the voltmeter 11A isabove Vt1, it is estimated that the power transmission distance is aboveD1, and the maximum power transmission efficiency is obtained. Afterthat, when the detection value of the voltmeter 11A is above Vt2, it isestimated that the power transmission distance is above D2, and thepower transmission efficiency is below the maximum power transmissionefficiency.

In contrast, when the power reception apparatus 20 is moved away fromthe power transmission apparatus 10, the detection value of thevoltmeter 21A continues to decrease. When the detection value of thevoltmeter 21A is below Vr1, it is estimated that the power transmissiondistance becomes longer than Dmax, and the power transmission distanceis above the allowable maximum distance.

(Control Method)

In the following, a control method according to the seventh embodimentis described. FIG. 20 is a flow diagram illustrating the control methodaccording to the seventh embodiment. Here, the power reception apparatus20 is a portable equipment, for example, any one of the remotecontroller 210, the smart phone 220, and the tablet terminal 230illustrated in FIG. 18, and performs transmission and reception of thesearch signal and the authentication ID in advance with the powertransmission apparatus 10, and is authenticated as the powertransmission target power reception apparatus 20.

As illustrated in FIG. 20, in step S110, the EMS 30 acquires the powertransmission distance for each power reception voltage of the powerreception apparatus 20.

In step S120, the EMS 30 sets the power reception voltage thresholdvalue corresponding to the allowable maximum distance. The powerreception voltage threshold value is a power reception voltage in a casewhere the power transmission distance is the allowable maximum distance,and corresponds to the voltage value Vr1 of FIG. 19B.

In step S130, the EMS 30 acquires the power reception voltage.Specifically, the EMS 30 acquires the power reception voltage byreceiving information indicating the power reception voltage from thepower reception apparatus 20.

In step S140, the EMS 30 determines whether or not the power receptionvoltage acquired is below the power reception voltage threshold value(voltage value Vr1). When the determination result is YES, the EMS 30proceeds to processing of step S150. In step S150, the EMS 30 stopspower transmission of the power transmission apparatus 10. On the otherhand, when the determination result is NO, the EMS 30 ends theprocessing and continues the power transmission of the powertransmission apparatus 10.

As described above, in the seventh embodiment, the EMS 30 estimates thepower transmission distance based on the power reception voltage of thepower reception apparatus 20, and determines that the power transmissiondistance is above the allowable maximum distance Dmax when the powerreception voltage of the power reception apparatus 20 is below the powerreception voltage threshold value, and stops the power transmission ofthe power transmission apparatus 10. Thus, when the power transmissiondistance is above the allowable maximum distance defined in the productspecification, the power transmission can be stopped of the powertransmission apparatus 10.

In addition, in the seventh embodiment, the EMS 30 can use the receivedsignal intensity of the signal received from the power transmissionapparatus 10 by the power reception apparatus 20, for estimation of thepower transmission distance. That is, the EMS 30 can stop the powertransmission of the power transmission apparatus 10 when the powerreception voltage acquired is below the power reception voltagethreshold value (voltage value Vr1), and the received signal intensityacquired from the power reception apparatus 20 is below the receivedsignal intensity corresponding to the allowable maximum distance. Byusing both of the power reception voltage and the received signalintensity for estimation of the power transmission distance, estimationaccuracy can be improved, and the power transmission can be reliablystopped of the power transmission apparatus 10 when needed.

[Modification]

Hereinafter, a control method is described according to a modificationof the seventh embodiment. FIG. 21 is a flow diagram illustrating thecontrol method according to the modification of the seventh embodiment.Here, description is appropriately omitted of a common part to theseventh embodiment, and a difference from the seventh embodiment ismainly described.

In the seventh embodiment, although the power transmission distance isestimated based on the power reception voltage of the power receptionapparatus 20, in the modification, the power transmission distance isestimated based on the power transmission voltage of the powertransmission apparatus 10.

As illustrated in FIG. 21, in step S210, the EMS 30 acquires the powertransmission efficiency for each power transmission voltage.

In step S220, the EMS 30 sets a threshold value corresponding to themaximum power transmission efficiency. Specifically, the EMS 30 sets thepower transmission voltage at the time of initial power transmission ofthe power transmission apparatus 10 as the power transmission voltagethreshold value. The power transmission voltage at the time of initialpower transmission of the power transmission apparatus is a powertransmission voltage in a case where power is transmitted in a state inwhich the power transmission target power reception apparatus 20 is notdetected, and corresponds to Vt2 of FIG. 19B.

In step S230, the EMS 30 acquires the power transmission voltage.Specifically, the EMS 30 acquires the power transmission voltage byreceiving information indicating the power transmission voltage from thepower transmission apparatus 10.

In step S240, the EMS 30 determines whether or not the powertransmission voltage acquired is above the power transmission voltagethreshold value (voltage value Vt2). When the determination result isYES, the EMS 30 proceeds to processing of step S250. In step S250, theEMS 30 stops the power transmission of the power transmission apparatus10. On the other hand, when the determination result is NO, the EMS 30ends the processing and continues the power transmission of the powertransmission apparatus 10.

As described above, in the modification, the EMS 30 estimates the powertransmission distance based on the power transmission voltage of thepower transmission apparatus 10, and determines that the powertransmission distance is above D2 and the power transmission efficiencyis below the maximum power transmission efficiency when the powertransmission voltage of the power transmission apparatus 10 is above thepower transmission voltage threshold value, and stops the powertransmission of the power transmission apparatus 10. Thus, when thepower transmission efficiency is below the maximum power transmissionefficiency, the power transmission can be stopped of the powertransmission apparatus 10.

In addition, in the modification, the EMS 30 can use the received signalintensity of the signal received from the power transmission apparatus10 by the power reception apparatus 20, for estimation of the powertransmission distance. That is, the EMS 30 can stop the powertransmission of the power transmission apparatus 10 when the powertransmission voltage acquired is above the power transmission voltagethreshold value (voltage value Vt2), and the received signal intensityacquired from the power reception apparatus 20 is below the receivedsignal intensity corresponding to the distance D2. By using both of thepower transmission voltage and the received signal intensity forestimation of the power transmission distance, estimation accuracy canbe improved, and the power transmission can be reliably stopped of thepower transmission apparatus 10 when needed.

Other Embodiments

Although the present disclosure has been described according to theabove embodiments, it should not be understood that the descriptions andthe drawings configuring a part of the disclosure limit the disclosure.Various alternative embodiments, examples, and operational techniqueswill be apparent to those skilled in the art from the disclosure.

In the embodiments, communication between the power transmissionapparatus 10 and the power reception apparatus 20 is performed by usingcommunication modules (communication module 13 and communication module23). However, the embodiments are not limited thereto. For example, thecommunication between the power transmission apparatus 10 and the powerreception apparatus 20 can be performed by using a power transmissionmodule 12 and a power reception module 22 (in-band communication).

In the embodiments, the case has been exemplified in which the powercontrol unit configured to control the transmission power of the powertransmission apparatus 10 is provided to the power transmissionapparatus 10. However, the embodiments are not limited thereto. Thepower control unit configured to control the transmission power of thepower transmission apparatus 10 can be provided to the EMS such as theHEMS.

In the second embodiment, the trigger E for transitioning to the standbystate from the power transmission state is occurrence of an event inwhich all of the power transmission target power reception apparatuses20 detected are no longer detected. However, the second embodiment isnot limited thereto. For example, the trigger E can be an event in whichtemperature is above a predetermined threshold value of a component (forexample, capacitor C or inductance L) configuring the power transmissionapparatus 10 in the power transmission state. Alternatively, on thepremise that the power transmission apparatus 10 receives the receptionpower information indicating an amount of power received by the powerreception apparatus 20, the trigger E is occurrence of an event in whichthe reception power information is below the predetermined thresholdvalue (for example, 10% of the reference power (Wref)). Alternatively,the trigger E is occurrence of an event in which, when the receptionpower information is below a predetermined threshold value, even if thetransmission power of the power transmission apparatus 10 increases, thestate is not be canceled in which the reception power information isbelow the predetermined threshold value. In addition, the powerreception apparatus can transmit to the power transmission apparatus 10information indicating abnormality when the reception power is smallerthan predetermined power, and the power transmission apparatus 10receiving the information can transition to the stop state from thepower transmission state. Incidentally, the power transmission apparatus10 can issue a warning when the information is received.

In the second embodiment, the trigger E has been mainly described fortransitioning to the standby state from the power transmission state.However, the trigger F for transitioning to the standby state from theintermittent power transmission state can also be the event same as thetrigger E.

In the fifth embodiment, the case has been exemplified in which theresonance control unit configured to control the resonance state of thepower reception side resonator 21 is provided to the power receptionapparatus 20. However, the fifth embodiment is not limited thereto. Theresonance control unit configured to control the resonance state of thepower reception side resonator 21 can be provided to the EMS such as theHEMS.

In the sixth embodiment, the case has been exemplified in which theamount of transmission power per unit time is controlled in two steps.However, the sixth embodiment is not limited thereto. The amount oftransmission power per unit time can be controlled in three steps ormore steps.

In the sixth embodiment, although the first power transmission state andthe second power transmission state are provided as separate states, thesixth embodiment is not limited thereto. The first power transmissionstate and the second power transmission state can be states configuringpart of the power transmission state. Similarly, in the sixthembodiment, although the first intermittent power transmission state andthe second intermittent power transmission state are provided asseparate states, the sixth embodiment is not limited thereto. The firstintermittent power transmission state and the second intermittent powertransmission state can be states configuring part of the intermittentpower transmission state.

In the seventh embodiment, the case has been exemplified in which thecontrol unit configured to control the transmission power of the powertransmission apparatus 10 is provided to the EMS 30. However, theseventh embodiment is not limited thereto. The control unit configuredto control the transmission power of the power transmission apparatus 10can be provided to, for example, a communication module (control unit13B) of the power transmission apparatus 10.

Although it is not particularly mentioned in the embodiments, a programcan be provided with which a computer executes each processing performedby the power transmission apparatus 10 and the power reception apparatus20. In addition, the program can be recorded in a computer readablemedium. When using the computer readable medium, it is possible toinstall the program to the computer. Here, the computer readable mediumrecording the program can be a non-transitory recording medium. Thenon-transitory recording medium, it is not particularly limited, can bea recording medium such as CD-ROM or DVD-ROM, for example.

Alternatively, a chip can be provided configured by a memory for storingthe program for executing each processing performed by the powertransmission apparatus 10 and the power reception apparatus 20, and aprocessor for executing the program stored in the memory.

INDUSTRIAL APPLICABILITY

According to the present disclosure, a control apparatus can be providedcapable of detecting a power transmission target power receptionapparatus without depending on a power state of the power receptionapparatus.

1. A control apparatus used in a power transmission system fortransmitting power with a magnetic resonance manner to a power receptionapparatus from a power transmission apparatus, the control apparatuscomprising a power controller configured to control a first powertransmission state in which power is transmitted at a first amount ofpower, and a second power transmission state in which power istransmitted at a second amount of power greater than the first amount ofpower.
 2. The control apparatus according to claim 1, wherein in thefirst power transmission state, the power is transmitted at the firstamount of power in a state in which a power transmission target powerreception apparatus is not detected, and in the second powertransmission state, the power is transmitted at the second amount ofpower in a state in which the power transmission target power receptionapparatus is detected
 3. The control apparatus according to claim 1,wherein the power controller controls transmission power of the powertransmission apparatus to transmit power at the first amount of power inthe first power transmission state, and the power controller controlstransmission power of the power transmission apparatus to transmit powerat the second amount of power greater than the first amount of power inthe second power transmission state.
 4. The control apparatus accordingto claim 1, wherein the power controller controls the power transmissionof the power transmission apparatus to intermittently transmit power ata first frequency in the first power transmission state, and the powercontroller controls the power transmission of the power transmissionapparatus to intermittently transmit power at a second frequency higherthan the first frequency in the second power transmission state.
 5. Thecontrol apparatus according to claim 1, wherein the power controllertransitions to the second power transmission state when the number ofpower transmission target power reception apparatuses is greater than apredetermined number.
 6. The control apparatus according to claim 1,wherein the power controller transitions to the second powertransmission state when a power reception apparatus having anapplication in which an amount of variation in power consumption isgreater than a predetermined value is included as a power transmissiontarget power reception apparatus.
 7. The control apparatus according toclaim 1, wherein the power controller transitions to the second powertransmission state when a request for executing an application of highpower consumption is received from the power transmission target powerreception apparatus, or when a request for transitioning to a high loadstate is received from the power transmission target power receptionapparatus.